Science.gov

Sample records for mammalogy trends biases

  1. Temperature trend biases

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2016-04-01

    In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

  2. Influences on the selection of content in mammalogy courses: A quantitative and qualitative study

    NASA Astrophysics Data System (ADS)

    Holden, James R.

    course content. The interviewees indicated interaction with other instructors was centered on research interests. An effort should be made to involve the American Society of Mammalogists in the teaching of mammalogy. Instructors should be aware of the role they play in the professional development of future marnmalogy instructors. Other upper-level undergraduate organismal courses should be researched to determine differences and this study should be repeated at regular intervals to gauge trends.

  3. Support for Society for Marine Mammalogy 2015 Biennial Conference

    DTIC Science & Technology

    2015-09-30

    Communicating Science Speakers: • Jane Lubchenco – Distinguished Professor of Zoology and Valley Professor of Marine Biology , Oregon State University...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. FINAL REPORT Support for Society for Marine Mammalogy 2015...Biennial Conference Frances Gulland The Marine Mammal Center 2000 Bunker Rd. Fort Cronkhite Sausolito, CA 94965 phone: (415) 289-7344 fax

  4. Bias of animal population trend estimates

    USGS Publications Warehouse

    Geissler, P.H.; Link, W.A.; Wegman, E.J.; Gantz, D.T.; Miller, J.J.

    1988-01-01

    A computer simulation study of the population trend estimator used for the Mourning Dove Call-Count Survey, Woodcock Singing Ground Survey, Breeding Bird Survey and other surveys concluded that the estimator had negligible bias in most situations but that observer covariables should not be used with less than five years of data. With rare species (e.g. two birds per route), at least five years should be used. The estimator is seriously biased towards not detecting population changes with very rare species (e.g. 0.3 birds per route). Other technical recommendations are made.

  5. New Trends in Magnetic Exchange Bias

    NASA Astrophysics Data System (ADS)

    Mougin, Alexandra; Mangin, Stéphane; Bobo, Jean-Francois; Loidl, Alois

    2005-05-01

    The study of layered magnetic structures is one of the hottest topics in magnetism due to the growing attraction of applications in magnetic sensors and magnetic storage media, such as random access memory. For almost half a century, new discoveries have driven researchers to re-investigate magnetism in thin film structures. Phenomena such as giant magnetoresistance, tunneling magnetoresistance, exchange bias and interlayer exchange coupling led to new ideas to construct devices, based not only on semiconductors but on a variety of magnetic materials Upon cooling fine cobalt particles in a magnetic field through the Néel temperature of their outer antiferromagnetic oxide layer, Meiklejohn and Bean discovered exchange bias in 1956. The exchange bias effect through which an antiferromagnetic AF layer can cause an adjacent ferromagnetic F layer to develop a preferred direction of magnetization, is widely used in magnetoelectronics technology to pin the magnetization of a device reference layer in a desired direction. However, the origin and effects due to exchange interaction across the interface between antiferromagneic and ferromagnetic layers are still debated after about fifty years of research, due to the extreme difficulty associated with the determination of the magnetic interfacial structure in F/AF bilayers. Indeed, in an AF/F bilayer system, the AF layer acts as “the invisible man” during conventional magnetic measurements and the presence of the exchange coupling is evidenced indirectly through the unusual behavior of the adjacent F layer. Basically, the coercive field of the F layer increases in contact with the AF and, in some cases, its hysteresis loop is shifted by an amount called exchange bias field. Thus, AF/F exchange coupling generates a new source of anisotropy in the F layer. This induced anisotropy strongly depends on basic features such as the magnetocrystalline anisotropy, crystallographic and spin structures, defects, domain patterns etc

  6. Evolutionary Trends and the Salience Bias (with Apologies to Oil Tankers, Karl Marx, and Others).

    ERIC Educational Resources Information Center

    McShea, Daniel W.

    1994-01-01

    Examines evolutionary trends, specifically trends in size, complexity, and fitness. Notes that documentation of these trends consists of either long lists of cases, or descriptions of a small number of salient cases. Proposes the use of random samples to avoid this "saliency bias." (SR)

  7. Evolutionary Trends and the Salience Bias (with Apologies to Oil Tankers, Karl Marx, and Others).

    ERIC Educational Resources Information Center

    McShea, Daniel W.

    1994-01-01

    Examines evolutionary trends, specifically trends in size, complexity, and fitness. Notes that documentation of these trends consists of either long lists of cases, or descriptions of a small number of salient cases. Proposes the use of random samples to avoid this "saliency bias." (SR)

  8. Sponsorship of the Society for Marine Mammalogy’s 19th Biennial Conference on the Biology of Marine Mammals

    DTIC Science & Technology

    2011-09-30

    response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing...and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information...Number: N00014110559 http://www.marinemammalscience.org/ LONG-TERM GOALS The Society for Marine Mammalogy ( SMM ), the world’s premier

  9. Oligonucleotide bias in Bacillus subtilis: general trends and taxonomic comparisons.

    PubMed Central

    Rocha, E P; Viari, A; Danchin, A

    1998-01-01

    We present a general analysis of oligonucleotide usage in the complete genome of Bacillus subtilis . Several datasets were built in order to assign various biological contexts to the biased use of words and to reveal local asymmetries in word usage that may be coupled with replication, the control of gene expression and the restriction/modification system. This analysis was complemented by cross-comparisons with the complete genomes of Escherichia coli , Haemophilus influenzae and Methanococcus jannaschii . We have observed a large number of biased oligonucleotides for words of size up to 8, throughout the datasets and species, indicating that such long strict words play an important role as biological signals. We speculate that some of them are involved in interactions with DNA and/or RNA polymerases. An extensive analysis of palindrome abundances and distributions provides the surprising result that prophage-like elements embedded in the genome exhibit a smaller avoidance of restriction sites. This may reinforce a recently proposed hypothesis of a selfish gene phenomena in the transfer of restriction/modification systems in bacteria. PMID:9611243

  10. The Influence of Logger Bias on Reported Temperature Trends: Implications for Temperature Monitoring Networks

    NASA Astrophysics Data System (ADS)

    Malcolm, I.; Fryer, R. J.; Bacon, P. J.; Stirling, D.

    2015-12-01

    There has been increasing interest in river temperature monitoring and research in recent years. This has been driven by factors including a greater awareness of the importance of river temperature for freshwater ecology, the potential for detrimental extremes under climate change and the availability of increasingly affordable dataloggers. A number of studies have attempted to collate and analyse pre-existing long-term (decadal) datasets to assess for evidence of temporal trends. These studies require considerable care given the magnitude of temporal trends (often < 1 degree per decade), the low signal to noise ratio in the data and the potential for bias across different makes, models and individual dataloggers. Despite these issues, data quality control often receives only a superficial consideration with subjective assessments of data quality or a reliance on manufacturer reported accuracy with consequences for the reliability and interpretation of findings. This study assessed the potential influence of logger bias on reported temperature trends in the Girnock Burn, Scotland over > 25 years. The bias of temperature measurements made by different dataloggers (two makes and five models) was determined through cross-calibration against a reference datalogger. Long-term trends in stream temperature metrics (daily mean, max, min) were characterised using Generalised Additive Mixed Models (GAMM). Models were fitted to (1) the raw data and (2) data corrected for logger bias. Significant non-linear temporal trends were observed in the raw data. These trends were accentuated when corrected for logger bias. Given the potential to accentuate or remove long-term trends, it is suggested that robust internal and external calibration and quality control procedures should be established for new temperature networks. Such approaches are capable of removing logger bias and improving accuracy by an order of magnitude over manufacturer stated values.

  11. Chronological bias in randomized clinical trials arising from different types of unobserved time trends.

    PubMed

    Tamm, M; Hilgers, R-D

    2014-01-01

    In clinical trials patients are commonly recruited sequentially over time incurring the risk of chronological bias due to (unobserved) time trends. To minimize the risk of chronological bias, a suitable randomization procedure should be chosen. Considering different time trend scenarios, we aim at a detailed evaluation of the extent of chronological bias under permuted block randomization in order to provide recommendations regarding the choice of randomization at the design stage of a clinical trial and to assess the maximum extent of bias for a realized sequence in the analysis stage. For the assessment of chronological bias we consider linear, logarithmic and stepwise trends illustrating typical changes during recruitment in clinical practice. Bias and variance of the treatment effect estimator as well as the empirical type I error rate when applying the t-test are investigated. Different sample sizes, block sizes and strengths of time trends are considered. Using large block sizes, a notable bias exists in the estimate of the treatment effect for specific sequences. This results in a heavily inflated type I error for realized worst-case sequences and an enlarged mean squared error of the treatment effect estimator. Decreasing the block size restricts these effects of time trends. Already applying permuted block randomization with two blocks instead of the random allocation rule achieves a good reduction of the mean squared error and of the inflated type I error. Averaged over all sequences, the type I error of the t-test is far below the nominal significance level due to an overestimated variance. Unobserved time trends can induce a strong bias in the treatment effect estimate and in the test decision. Therefore, already in the design stage of a clinical trial a suitable randomization procedure should be chosen. According to our results, small block sizes should be preferred, but also medium block sizes are sufficient to restrict chronological bias to an

  12. Review of mammalogical research in the Guianas of northern South America.

    PubMed

    Lim, Burton K

    2016-03-01

    Research on mammals in the Guianas of northern South America has had a checkered history. In this review, I summarize the notable contributions to mammalogical study in Guyana, Suriname and French Guiana. These studies began in the mid-18th century with the binomial nomenclature system of scientific classification created by the Swedish naturalist Carl Linnaeus, who described 23 species new to science based on holotype specimens from the Guianas. Notwithstanding popular accounts by amateur naturalists visiting this region, over the next 7 decades there was only sporadic taxonomic work done on Guianan mammals primarily by researchers at European museums. The first comprehensive biological exploration took place in the 1840s during a geographic survey of the boundaries of British Guiana. However, it was not until almost half a century later that scientific publications began to regularly document the increasing species diversity in the region, including the prodigious work of Oldfield Thomas at the British Museum of Natural History in London. Another lull in the study of mammals occurred in the mid-1910s to the early 1960s after which foreign researchers began to rediscover the Guianas and their pristine habitats. This biological renaissance is still ongoing and I give a prospectus on the direction of future research in one of the last frontiers of tropical rainforest. An initiative that would be greatly beneficial is the establishment of a university network in the Guianas with graduate-based research to develop a cadre of professional experts on biodiversity and evolution as seen in other countries of South America. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  13. Modeling Systematic Change in Stopover Duration Does Not Improve Bias in Trends Estimated from Migration Counts

    PubMed Central

    Crewe, Tara L.; Taylor, Philip D.; Lepage, Denis

    2015-01-01

    The use of counts of unmarked migrating animals to monitor long term population trends assumes independence of daily counts and a constant rate of detection. However, migratory stopovers often last days or weeks, violating the assumption of count independence. Further, a systematic change in stopover duration will result in a change in the probability of detecting individuals once, but also in the probability of detecting individuals on more than one sampling occasion. We tested how variation in stopover duration influenced accuracy and precision of population trends by simulating migration count data with known constant rate of population change and by allowing daily probability of survival (an index of stopover duration) to remain constant, or to vary randomly, cyclically, or increase linearly over time by various levels. Using simulated datasets with a systematic increase in stopover duration, we also tested whether any resulting bias in population trend could be reduced by modeling the underlying source of variation in detection, or by subsampling data to every three or five days to reduce the incidence of recounting. Mean bias in population trend did not differ significantly from zero when stopover duration remained constant or varied randomly over time, but bias and the detection of false trends increased significantly with a systematic increase in stopover duration. Importantly, an increase in stopover duration over time resulted in a compounding effect on counts due to the increased probability of detection and of recounting on subsequent sampling occasions. Under this scenario, bias in population trend could not be modeled using a covariate for stopover duration alone. Rather, to improve inference drawn about long term population change using counts of unmarked migrants, analyses must include a covariate for stopover duration, as well as incorporate sampling modifications (e.g., subsampling) to reduce the probability that individuals will be detected on

  14. Citizen science: best practices to remove observer bias in trend analysis.

    PubMed

    Gonsamo, Alemu; D'Odorico, Petra

    2014-12-01

    Citizen science, time series records over long periods of time, and wide geographic areas offer many opportunities for scientists to answer questions that would otherwise be impractical to investigate. Citizen scientists currently play active roles in a wide range of ecological projects; however, observer biases such as varying perception of events or objects being observed and quality of observations present challenges to successfully derive interannual variability and trend statistics from time series records. It is recommended that citizen science records, particularly those involving events such as plant phenology, should not be directly averaged across sites. The interannual variability expressed as an anomaly and trend expressed as a regression slope should be calculated for each site. Only the site level anomaly and regression slopes should be averaged to suppress observer biases.

  15. Cor­rection of stream quality trends for the effects of laboratory mea­surement bias

    USGS Publications Warehouse

    Alexander, Richard B.; Smith, Richard A.; Schwarz, Gregory E.

    1993-01-01

    We present a statistical model relating measurements of water quality to associated errors in laboratory methods. Estimation of the model allows us to correct trends in water quality for long-term and short-term variations in laboratory measurement errors. An illustration of the bias correction method for a large national set of stream water quality and quality assurance data shows that reductions in the bias of estimates of water quality trend slopes are achieved at the expense of increases in the variance of these estimates. Slight improvements occur in the precision of estimates of trend in bias by using correlative information on bias and water quality to estimate random variations in measurement bias. The results of this investigation stress the need for reliable, long-term quality assurance data and efficient statistical methods to assess the effects of measurement errors on the detection of water quality trends.

  16. Use of Multiple Imputation to Correct for Bias in Lung Cancer Incidence Trends by Histologic Subtype

    PubMed Central

    Yu, Mandi; Feuer, Eric J.; Cronin, Kathleen A.; Caporaso, Neil E.

    2014-01-01

    Background Over the past several decades, advances in lung cancer research and practice have led to refinements of histological diagnosis of lung cancer. The differential use and subsequent alterations of non-specific morphology codes, however, may have caused artifactual fluctuations in the incidence rates for histologic subtypes, thus biasing temporal trends. Methods We developed a multiple imputation (MI) method to correct lung cancer incidence for non-specific histology using data from the Surveillance, Epidemiology, and End Results (SEER) Program during 1975–2010. Results For adenocarcinoma in men and squamous in both genders, the change to a increasing trend around 2005, after more than ten years of decreasing incidence, is apparently an artifact of the changes in histopathology practice and coding system. After imputation, the rates remained decreasing for adenocarcinoma and squamous in men, and became constant for squamous in women. Conclusions As molecular features of distinct histologies are increasingly identified by new technologies, accurate histological distinctions are becoming increasingly relevant to more effective 'targeted' therapies, and therefore, are important to track in patients. However, without incorporating the coding changes, the incidence trends estimated for histologic subtypes could be misleading. Impact The MI approach provides a valuable tool for bridging the different histology definitions, thus permitting meaningful inferences about the long-term trends of lung cancer by histological subtype. PMID:24855099

  17. Use of multiple imputation to correct for bias in lung cancer incidence trends by histologic subtype.

    PubMed

    Yu, Mandi; Feuer, Eric J; Cronin, Kathleen A; Caporaso, Neil E

    2014-08-01

    Over the past several decades, advances in lung cancer research and practice have led to refinements of histologic diagnosis of lung cancer. The differential use and subsequent alterations of nonspecific morphology codes, however, may have caused artifactual fluctuations in the incidence rates for histologic subtypes, thus biasing temporal trends. We developed a multiple imputation (MI) method to correct lung cancer incidence for nonspecific histology using data from the Surveillance, Epidemiology, and End Results Program during 1975 to 2010. For adenocarcinoma in men and squamous in both genders, the change to an increasing trend around 2005, after more than 10 years of decreasing incidence, is apparently an artifact of the changes in histopathology practice and coding system. After imputation, the rates remained decreasing for adenocarcinoma and squamous in men, and became constant for squamous in women. As molecular features of distinct histologies are increasingly identified by new technologies, accurate histologic distinctions are becoming increasingly relevant to more effective "targeted" therapies, and therefore, are important to track in patients. However, without incorporating the coding changes, the incidence trends estimated for histologic subtypes could be misleading. The MI approach provides a valuable tool for bridging the different histology definitions, thus permitting meaningful inferences about the long-term trends of lung cancer by histologic subtype. ©2014 American Association for Cancer Research.

  18. Quantifying the Economic and Cultural Biases of Social Media through Trending Topics

    PubMed Central

    Carrascosa, Juan Miguel; Cuevas, Ruben; Gonzalez, Roberto; Azcorra, Arturo; Garcia, David

    2015-01-01

    Online social media has recently irrupted as the last major venue for the propagation of news and cultural content, competing with traditional mass media and allowing citizens to access new sources of information. In this paper, we study collectively filtered news and popular content in Twitter, known as Trending Topics (TTs), to quantify the extent to which they show similar biases known for mass media. We use two datasets collected in 2013 and 2014, including more than 300.000 TTs from 62 countries. The existing patterns of leader-follower relationships among countries reveal systemic biases known for mass media: Countries concentrate their attention to small groups of other countries, generating a pattern of centralization in which TTs follow the gradient of wealth across countries. At the same time, we find subjective biases within language communities linked to the cultural similarity of countries, in which countries with closer cultures and shared languages tend to follow each other’s TTs. Moreover, using a novel methodology based on the Google News service, we study the influence of mass media in TTs for four countries. We find that roughly half of the TTs in Twitter overlap with news reported by mass media, and that the rest of TTs are more likely to spread internationally within Twitter. Our results confirm that online social media have the power to independently spread content beyond mass media, but at the same time social media content follows economic incentives and is subject to cultural factors and language barriers. PMID:26230656

  19. Quantifying the Economic and Cultural Biases of Social Media through Trending Topics.

    PubMed

    Carrascosa, Juan Miguel; Cuevas, Ruben; Gonzalez, Roberto; Azcorra, Arturo; Garcia, David

    2015-01-01

    Online social media has recently irrupted as the last major venue for the propagation of news and cultural content, competing with traditional mass media and allowing citizens to access new sources of information. In this paper, we study collectively filtered news and popular content in Twitter, known as Trending Topics (TTs), to quantify the extent to which they show similar biases known for mass media. We use two datasets collected in 2013 and 2014, including more than 300.000 TTs from 62 countries. The existing patterns of leader-follower relationships among countries reveal systemic biases known for mass media: Countries concentrate their attention to small groups of other countries, generating a pattern of centralization in which TTs follow the gradient of wealth across countries. At the same time, we find subjective biases within language communities linked to the cultural similarity of countries, in which countries with closer cultures and shared languages tend to follow each other's TTs. Moreover, using a novel methodology based on the Google News service, we study the influence of mass media in TTs for four countries. We find that roughly half of the TTs in Twitter overlap with news reported by mass media, and that the rest of TTs are more likely to spread internationally within Twitter. Our results confirm that online social media have the power to independently spread content beyond mass media, but at the same time social media content follows economic incentives and is subject to cultural factors and language barriers.

  20. A Nonresponse Bias Analysis of the Health Information National Trends Survey (HINTS).

    PubMed

    Maitland, Aaron; Lin, Amy; Cantor, David; Jones, Mike; Moser, Richard P; Hesse, Bradford W; Davis, Terisa; Blake, Kelly D

    2017-07-01

    We conducted a nonresponse bias analysis of the Health Information National Trends Survey (HINTS) 4, Cycles 1 and 3, collected in 2011 and 2013, respectively, using three analysis methods: comparison of response rates for subgroups, comparison of estimates with weighting adjustments and external benchmarks, and level-of-effort analysis. Areas with higher concentrations of low socioeconomic status, higher concentrations of young households, and higher concentrations of minority and Hispanic populations had lower response rates. Estimates of health information seeking behavior were higher in HINTS compared to the National Health Interview Survey (NHIS). The HINTS estimate of doctors always explaining things in a way that the patient understands was not significantly different from the same estimate from the Medical Expenditure Panel Survey (MEPS); however, the HINTS estimate of health professionals always spending enough time with the patient was significantly lower than the same estimate from MEPS. A level-of-effort analysis found that those who respond later in the survey field period were less likely to have looked for information about health in the past 12 months, but found only small differences between early and late respondents for the majority of estimates examined. There is some evidence that estimates from HINTS could be biased toward finding higher levels of health information seeking.

  1. Trends and biases in global scientific literature about ecological niche models.

    PubMed

    Vaz, U L; Cunha, H F; Nabout, J C

    2015-11-01

    Recently, ecological niche models have been employed to investigate the potential geographical distribution of species. However, it is necessary to analyze the vast number of publications on this topic to understand the trends and biases of research using ecological niche models (ENMs). Therefore, this study aims to investigate trends in the scientific literature regarding studies on ENMs. For the quantitative analysis of the literature on ENMs, we performed a search in the Thomson ISI (Web of Science) database between 1991 and 2013. The search identified 3042 papers containing preselected keywords in either the title or abstract. The results showed that the number of papers has increased over the years (r=0.77, P<0.001), with a sharp increase in recent years, highlighting the widespread use of the ENMs. There was an increase in the diversity of journals that published papers about ENMs (r=0.97, P<0.001). The research was conducted in different countries, predominantly the United States of America (550 papers), and the most commonly used method was the Maximum Entropy method (312 papers). Regarding the taxonomic group, most research has been conducted on plants (402 papers, or 28.36% of the total). There was no relationship between the modeling method used and the taxonomic group studied (χ2=4.8, P=0.15). Finally, the wide availability of biological, environmental and computational resources has elicited the broad use of tools for ENMs. Despite the conceptual discussions of the ENMs, this method is currently the most effective way to evaluate the potential geographical distribution of species, and to predict the distribution under different environmental conditions (i.e., future or past scenarios).

  2. Modeling a secular trend by Monte Carlo simulation of height biased migration in a spatial network.

    PubMed

    Groth, Detlef

    2017-04-01

    Background: In a recent Monte Carlo simulation, the clustering of body height of Swiss military conscripts within a spatial network with characteristic features of the natural Swiss geography was investigated. In this study I examined the effect of migration of tall individuals into network hubs on the dynamics of body height within the whole spatial network. The aim of this study was to simulate height trends. Material and methods: Three networks were used for modeling, a regular rectangular fishing net like network, a real world example based on the geographic map of Switzerland, and a random network. All networks contained between 144 and 148 districts and between 265-307 road connections. Around 100,000 agents were initially released with average height of 170 cm, and height standard deviation of 6.5 cm. The simulation was started with the a priori assumption that height variation within a district is limited and also depends on height of neighboring districts (community effect on height). In addition to a neighborhood influence factor, which simulates a community effect, body height dependent migration of conscripts between adjacent districts in each Monte Carlo simulation was used to re-calculate next generation body heights. In order to determine the direction of migration for taller individuals, various centrality measures for the evaluation of district importance within the spatial network were applied. Taller individuals were favored to migrate more into network hubs, backward migration using the same number of individuals was random, not biased towards body height. Network hubs were defined by the importance of a district within the spatial network. The importance of a district was evaluated by various centrality measures. In the null model there were no road connections, height information could not be delivered between the districts. Results: Due to the favored migration of tall individuals into network hubs, average body height of the hubs, and later

  3. This week?s Citation Classic: 'Stickel, L. F. A comparison of certain methods of measuring ranges of small mammals. J. Mammalogy 35: 1-15, 1954.'

    USGS Publications Warehouse

    Stickel, L.F.

    1986-01-01

    During my first employment as a junior biologist conducting food habits analyses at the Patuxent Research Refuge (now Patuxent Wildlife Research Center) of the US Fish and Wildlife Service, the first station director, Arnold L. Nelson, gave each staff biologist the opportunity to spend a little time conducting field studies on the 2,600-acre research area. These studies were to help in ecological evaluation of the area, but also, no doubt, functioned as a morale builder for biologists daily engaged in difficult, demanding and confining laboratory work. I undertook to measure the population density of small mammals in different habitats. The state-of-the-art methods recommended to me and prevalent in the literature worried me, especially after preliminary field work. Reading the classic, paper by W.H. Burt [Terrioriality and home range concepts as applied to mammals. J. Mammalogy 24:346-352, 1943] was a turning point for me in seeing that knowledge of home-range size was the key to measuring population density. My first papers employed these concepts in field evaluations. However, they could give-only limited attention to the question of how home ranges could be measured. Furthermore, the importance of knowledge of the home range to habitat evaluation and to understanding animal behavior was becoming increasingly apparent. Advocacy of many different methods of measuring home ranges appeared in the literature. It did not seem possible to evaluate them objectively. It occurred to me that artificial populations could be used to help in understanding the mechanisms of measuring home ranges. The effects of random trap-visiting, bias toward central traps, trap-spacing, range shape, and other factors could be considered. So grids of traps were inked onto oversize graph paper, and simulated ranges were cut from plastic to be tossed as randomly as possible on the trap-grids. It was a slow, laborious job. Analysis showed that random captures in artificial populations produced

  4. Model under-representation of decadal Pacific trade wind trends and its link to tropical Atlantic bias

    NASA Astrophysics Data System (ADS)

    Kajtar, Jules B.; Santoso, Agus; McGregor, Shayne; England, Matthew H.; Baillie, Zak

    2017-06-01

    The strengthening of the Pacific trade winds in recent decades has been unmatched in the observational record stretching back to the early twentieth century. This wind strengthening has been connected with numerous climate-related phenomena, including accelerated sea-level rise in the western Pacific, alterations to Indo-Pacific ocean currents, increased ocean heat uptake, and a slow-down in the rate of global-mean surface warming. Here we show that models in the Coupled Model Intercomparison Project phase 5 underestimate the observed range of decadal trends in the Pacific trade winds, despite capturing the range in decadal sea surface temperature (SST) variability. Analysis of observational data suggests that tropical Atlantic SST contributes considerably to the Pacific trade wind trends, whereas the Atlantic feedback in coupled models is muted. Atmosphere-only simulations forced by observed SST are capable of recovering the time-variation and the magnitude of the trade wind trends. Hence, we explore whether it is the biases in the mean or in the anomalous SST patterns that are responsible for the under-representation in fully coupled models. Over interannual time-scales, we find that model biases in the patterns of Atlantic SST anomalies are the strongest source of error in the precipitation and atmospheric circulation response. In contrast, on decadal time-scales, the magnitude of the model biases in Atlantic mean SST are directly linked with the trade wind variability response.

  5. Selection bias due to parity-conditioning in studies of time trends in fertility.

    PubMed

    Sallmén, Markku; Bonde, Jens Peter; Lindbohm, Marja-Liisa; Kristensen, Petter

    2015-01-01

    Studies of couple fertility over time have often examined study populations with broad age ranges at a cross-section of time. An increase in fertility has been observed in studies that followed episodes of fertility events either prospectively among nulliparous women or retrospectively among parous women. Fertility has a biological effect on parity. If defined at a cross-section of time, parity will also be affected by year of birth, and thus becomes a collider. Conditioning (stratifying, restricting, or adjusting) on a collider may cause selection bias in the studied association. A study with prospective follow-up was taken as the model to assess the validity of fertility studies. We demonstrate the potential for selection bias using causal graphs and nationwide birth statistics and other demographic data. We tested the existence of parity-conditioning bias in data including both parous and nulliparous women. We also used a simulation approach to assess the strength of the bias in populations with prior at-risk cycles. Finally, we evaluated the potential for selection bias due to conditioning on parity in various sampling frames. Analyses indicate that the observed increase in fertility over time can be entirely explained by selection bias due to parity-conditioning. Heterogeneity in fertility and differential success in prior at-risk cycles are the ultimate factors behind the selection bias. The potential for selection bias due to parity-conditioning varies by sampling frame. A prospective multidecade study with representative sampling of birth cohorts and follow-up from menarche to menopause would bypass the described bias.

  6. Precipitation collector bias and its effects on temporal trends and spatial variability in National Atmospheric Deposition Program/National Trends Network data

    USGS Publications Warehouse

    Wetherbee, Gregory A.

    2017-01-01

    Precipitation samples have been collected by the National Atmospheric Deposition Program's (NADP) National Trends Network (NTN) using the Aerochem Metrics Model 301 (ACM) collector since 1978. Approximately one-third of the NTN ACM collectors have been replaced with N-CON Systems, Inc. Model ADS 00-120 (NCON) collectors. Concurrent data were collected over 6 years at 12 NTN sites using colocated ACM and NCON collectors in various precipitation regimes. Linear regression models of the colocated data were used to adjust for relative bias between the collectors. Replacement of ACM collectors with NCON collectors resulted in shifts in 10-year seasonal precipitation-weighted mean concentration (PWMC) trend slopes for: cations (−0.001 to −0.007 mgL−1yr−1), anions (−0.009 to −0.028 mgL−1yr−1), and hydrogen ion (+0.689 meqL-1yr−1). Larger shifts in NO3− and SO4−2 seasonal PWMC trend slopes were observed in the Midwest and Northeast US, where concentrations are generally higher than in other regions. Geospatial analysis of interpolated concentration rasters indicated regions of accentuated variability introduced by incorporation of NCON collectors into the NTN.

  7. Child mortality estimation: methods used to adjust for bias due to AIDS in estimating trends in under-five mortality.

    PubMed

    Walker, Neff; Hill, Kenneth; Zhao, Fengmin

    2012-01-01

    In most low- and middle-income countries, child mortality is estimated from data provided by mothers concerning the survival of their children using methods that assume no correlation between the mortality risks of the mothers and those of their children. This assumption is not valid for populations with generalized HIV epidemics, however, and in this review, we show how the United Nations Inter-agency Group for Child Mortality Estimation (UN IGME) uses a cohort component projection model to correct for AIDS-related biases in the data used to estimate trends in under-five mortality. In this model, births in a given year are identified as occurring to HIV-positive or HIV-negative mothers, the lives of the infants and mothers are projected forward using survivorship probabilities to estimate survivors at the time of a given survey, and the extent to which excess mortality of children goes unreported because of the deaths of HIV-infected mothers prior to the survey is calculated. Estimates from the survey for past periods can then be adjusted for the estimated bias. The extent of the AIDS-related bias depends crucially on the dynamics of the HIV epidemic, on the length of time before the survey that the estimates are made for, and on the underlying non-AIDS child mortality. This simple methodology (which does not take into account the use of effective antiretroviral interventions) gives results qualitatively similar to those of other studies.

  8. Divergent Urban-Rural Trends in College Attendance: State Policy Bias and Structural Exclusion in China

    ERIC Educational Resources Information Center

    Tam, Tony; Jiang, Jin

    2015-01-01

    Despite the massive expansion of higher education in China since 1998, the cohort trends of urban and rural "hukou" holders in college attendance have widened sharply. Prevailing explanations emphasize the advantages of urban students over rural students in school quality and household financial resources. We propose the structural…

  9. Divergent Urban-Rural Trends in College Attendance: State Policy Bias and Structural Exclusion in China

    ERIC Educational Resources Information Center

    Tam, Tony; Jiang, Jin

    2015-01-01

    Despite the massive expansion of higher education in China since 1998, the cohort trends of urban and rural "hukou" holders in college attendance have widened sharply. Prevailing explanations emphasize the advantages of urban students over rural students in school quality and household financial resources. We propose the structural…

  10. Trends in Gender Bias Across Earth and Space Science Scholarly Publishing

    NASA Astrophysics Data System (ADS)

    Lerback, J. C.; Hanson, B.

    2016-12-01

    It has been challenging to assess gender bias across scholarly publishing in part because data on both gender and age are needed, as the proportion of women varies with age across most disciplines. To address this, we matched the member database of the American Geophysical Union (AGU), where age and gender are self-reported, with the AGU editorial database. The proportion of women members increased since 2013 across all disciplines from 24.6 to 26.9%. The proportion of women publishing as first authors increased across most disciplines and overall from 24.8 to 25.9%; however, it decreased in atmospheric science, global change, and planetary science. Overall, women had a higher acceptance rate than men across all in aggregate, 60.4 vs. 56.4% and equal or higher in all disciplines. Co-author behavior did not vary greatly across disciplines; most female first authors had 20% female co-authors, whereas male first authors have 15% female co-authors. Women were used less often as reviewers (17.9% of the time) than expected based on their membership in the society and their rate as accepted first authors (26.7% female) and all accepted authors (23.3%). Furthermore, the proportion of reviews done by women did not increase in several disciplines from 2012-2015, including atmospheric science, geology and geophysics, mathematical geophysics, and planetary science. The bias is a result of fewer suggestions of women reviewers by male authors and editors, and also a higher decline rate by women within each age cohort when asked to review. Invitations to women to review increased from 16.7% in 2012 to 18.5% in 2015 overall, but not in geology and geophysics, planetary sciences, and space sciences. Participating as a reviewer can have important career benefits; thus, addressing this bias is important for addressing pipeline issues and improving retention of women in the field.

  11. On the relaxation behaviors of slow and classical glitches: Observational biases and their opposite recovery trends

    SciTech Connect

    Xie, Yi; Zhang, Shuang-Nan

    2013-11-20

    We study the pulsar timing properties and the data analysis methods of glitch recoveries. In some cases one first fits the times of arrival (TOAs) to obtain the 'time-averaged' frequency ν and its first derivative ν-dot , and then fits models to them. However, our simulations show that ν and ν-dot obtained in this way are systematically biased unless the time intervals between the nearby data points of TOAs are smaller than about 10{sup 4} s, which is much shorter than typical observation intervals. Alternatively, glitch parameters can be obtained by fitting the phases directly with relatively smaller biases, but the initial recovery time scale is usually chosen by eye, which may introduce a strong bias. We also construct a phenomenological model by assuming a pulsar spin-down law of ν-dot ν{sup −3}=−H{sub 0}G(t) with G(t) = 1 + κe {sup –t/τ} for a glitch recovery, where H {sub 0} is a constant and κ and τ are the glitch parameters to be found. This model can reproduce the observed data of slow glitches from B1822–09 and the giant classical glitch of B2334+61, with κ < 0 or κ > 0, respectively. We then use this model to simulate TOA data and test several fitting procedures for a glitch recovery. The best procedure is (1) to use a very high order polynomial (e.g., to 50th order) to precisely describe the phase, (2) obtain ν(t) and ν-dot (t) from the polynomial, then (3) obtain the glitch parameters from ν(t) or ν-dot (t). Finally, the uncertainty in the starting time t {sub 0} of a classical glitch causes uncertainties in some glitch parameters, but less so for a slow glitch, t {sub 0}, of which can be determined from data.

  12. Corrigendum to: “Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: a re-analysis of Attewell, Glase and McFadden, 2001” [Accid. Anal. Prev. 43 (2011) 1245–1251].

    PubMed

    Elvik, Rune

    2013-11-01

    This paper is a corrigendum to the previously published paper: “Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: A re-analysis of Attewell, Glase and McFadden, 2001” [Accid. Anal. Prev. (2011) 1245–1251]. This corrigendum was prepared to correct errors in data and analysis in the previously published paper. Like the previously published paper, this paper confirms that the meta-analysis of bicycle helmet efficacy reported by Attewell, Glase and McFadden (Accident Analysis and Prevention, 2001, 345–352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets. This paper presents a re-analysis of the study. The re-analysis included: (1) Ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect relying on zero counts; (2) detecting and adjusting for publication bias by means of the trim-and-fill method; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets. The re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study.

  13. Sea Ice Trends in Climate Models Only Accurate in Runs with Biased Global Warming

    NASA Astrophysics Data System (ADS)

    Rosenblum, Erica; Eisenman, Ian

    2017-08-01

    Observations indicate that the Arctic sea ice cover is rapidly retreating while the Antarctic sea ice cover is steadily expanding. State-of-the-art climate models, by contrast, typically simulate a moderate decrease in both the Arctic and Antarctic sea ice covers. However, in each hemisphere there is a small subset of model simulations that have sea ice trends similar to the observations. Based on this, a number of recent studies have suggested that the models are consistent with the observations in each hemisphere when simulated internal climate variability is taken into account. Here we examine sea ice changes during 1979-2013 in simulations from the most recent Coupled Model Intercomparison Project (CMIP5) as well as the Community Earth System Model Large Ensemble (CESM-LE), drawing on previous work that found a close relationship in climate models between global-mean surface temperature and sea ice extent. We find that all of the simulations with 1979-2013 Arctic sea ice retreat as fast as observed have considerably more global warming than observations during this time period. Using two separate methods to estimate the sea ice retreat that would occur under the observed level of global warming in each simulation in both ensembles, we find that simulated Arctic sea ice retreat as fast as observed would occur less than 1% of the time. This implies that the models are not consistent with the observations. In the Antarctic, we find that simulated sea ice expansion as fast as observed typically corresponds with too little global warming, although these results are more equivocal. We show that because of this, the simulations do not capture the observed asymmetry between Arctic and Antarctic sea ice trends. This suggests that the models may be getting the right sea ice trends for the wrong reasons in both polar regions.

  14. Possible Biases of Researchers’ Attitudes Toward Video Games: Publication Trends Analysis of the Medical Literature (1980–2013)

    PubMed Central

    Rovner, Mitchell; Appel, David Ian; Abrams, Aaron W; Rotem, Michal; Bloch, Yuval

    2016-01-01

    Background The study of video games is expanding, and so is the debate regarding their possible positive and deleterious effects. As controversies continue, several researchers have expressed their concerns about substantial biases existing in the field, which might lead to the creation of a skewed picture, both in the professional and in the lay literature. However, no study has tried to examine this issue quantitatively. Objective The objective of our study was to examine possible systematic biases in the literature, by analyzing the publication trends of the medical and life sciences literature regarding video games. Methods We performed a complete and systematic PubMed search up to December 31, 2013. We assessed all 1927 articles deemed relevant for their attitude toward video games according to the focus, hypothesis, and authors’ interpretation of the study results, using a 3-category outcome (positive, negative, and neutral). We assessed the prevalence of different attitudes for possible association with year of publication, location of researchers, academic discipline, methodological research, and centrality of the publishing journals. Results The attitude toward video games presented in publications varied by year of publication, location, academic discipline, and methodological research applied (P<.001 for all). Moreover, representation of different attitudes differed according to centrality of the journals, as measured by their impact factor (P<.001). Conclusions The results suggest that context, whether scientific or social, is related to researchers’ attitudes toward video games. Readers, both lay and professional, should weigh these contextual variables when interpreting studies’ results, in light of the possible bias they carry. The results also support a need for a more balanced, open-minded approach toward video games, as it is likely that this complex phenomenon carries novel opportunities as well as new hazards. PMID:27430187

  15. Possible Biases of Researchers' Attitudes Toward Video Games: Publication Trends Analysis of the Medical Literature (1980-2013).

    PubMed

    Segev, Aviv; Rovner, Mitchell; Appel, David Ian; Abrams, Aaron W; Rotem, Michal; Bloch, Yuval

    2016-07-18

    The study of video games is expanding, and so is the debate regarding their possible positive and deleterious effects. As controversies continue, several researchers have expressed their concerns about substantial biases existing in the field, which might lead to the creation of a skewed picture, both in the professional and in the lay literature. However, no study has tried to examine this issue quantitatively. The objective of our study was to examine possible systematic biases in the literature, by analyzing the publication trends of the medical and life sciences literature regarding video games. We performed a complete and systematic PubMed search up to December 31, 2013. We assessed all 1927 articles deemed relevant for their attitude toward video games according to the focus, hypothesis, and authors' interpretation of the study results, using a 3-category outcome (positive, negative, and neutral). We assessed the prevalence of different attitudes for possible association with year of publication, location of researchers, academic discipline, methodological research, and centrality of the publishing journals. The attitude toward video games presented in publications varied by year of publication, location, academic discipline, and methodological research applied (P<.001 for all). Moreover, representation of different attitudes differed according to centrality of the journals, as measured by their impact factor (P<.001). The results suggest that context, whether scientific or social, is related to researchers' attitudes toward video games. Readers, both lay and professional, should weigh these contextual variables when interpreting studies' results, in light of the possible bias they carry. The results also support a need for a more balanced, open-minded approach toward video games, as it is likely that this complex phenomenon carries novel opportunities as well as new hazards.

  16. Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984

    USGS Publications Warehouse

    Brooks, M.H.; Schroder, L.J.; Willoughby, T.C.

    1987-01-01

    The U.S. Geological Survey operated a blind audit sample program during 1974 to test the effects of the sample handling and shipping procedures used by the National Atmospheric Deposition Program and National Trends Network on the quality of wet deposition data produced by the combined networks. Blind audit samples, which were dilutions of standard reference water samples, were submitted by network site operators to the central analytical laboratory disguised as actual wet deposition samples. Results from the analyses of blind audit samples were used to calculate estimates of analyte bias associated with all network wet deposition samples analyzed in 1984 and to estimate analyte precision. Concentration differences between double blind samples that were submitted to the central analytical laboratory and separate analyses of aliquots of those blind audit samples that had not undergone network sample handling and shipping were used to calculate analyte masses that apparently were added to each blind audit sample by routine network handling and shipping procedures. These calculated masses indicated statistically significant biases for magnesium, sodium , potassium, chloride, and sulfate. Median calculated masses were 41.4 micrograms (ug) for calcium, 14.9 ug for magnesium, 23.3 ug for sodium, 0.7 ug for potassium, 16.5 ug for chloride and 55.3 ug for sulfate. Analyte precision was estimated using two different sets of replicate measures performed by the central analytical laboratory. Estimated standard deviations were similar to those previously reported. (Author 's abstract)

  17. Continuously amplified warming in the Alaskan Arctic: Implications for estimating global warming hiatus: SPATIAL COVERAGE AND BIAS IN TREND

    DOE PAGES

    Wang, Kang; Zhang, Tingjun; Zhang, Xiangdong; ...

    2017-09-13

    Historically, in-situ measurements have been notoriously sparse over the Arctic. As a consequence, the existing gridded data of Surface Air Temperature (SAT) may have large biases in estimating the warming trend in this region. Using data from an expanded monitoring network with 31 stations in the Alaskan Arctic, we demonstrate that the SAT has increased by 2.19 °C in this region, or at a rate of 0.23 °C/decade during 1921-2015. Mean- while, we found that the SAT warmed at 0.71 °C/decade over 1998-2015, which is two to three times faster than the rate established from the gridded datasets. Focusing onmore » the "hiatus" period 1998-2012 as identied by the Intergovernmental Panel on Climate Change (IPCC) report, the SAT has increased at 0.45 °C/decade, which captures more than 90% of the regional trend for 1951- 2012. We suggest that sparse in-situ measurements are responsible for underestimation of the SAT change in the gridded datasets. It is likely that enhanced climate warming may also have happened in the other regions of the Arctic since the late 1990s but left undetected because of incomplete observational coverage.« less

  18. Correction Technique for Raman Water Vapor Lidar Signal-Dependent Bias and Suitability for Water Wapor Trend Monitoring in the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Whiteman, D. N.; Cadirola, M.; Venable, D.; Calhoun, M.; Miloshevich, L; Vermeesch, K.; Twigg, L.; Dirisu, A.; Hurst, D.; Hall, E.; Jordan, A.; Voemel, H.

    2012-01-01

    The MOHAVE-2009 campaign brought together diverse instrumentation for measuring atmospheric water vapor. We report on the participation of the ALVICE (Atmospheric Laboratory for Validation, Interagency Collaboration and Education) mobile laboratory in the MOHAVE-2009 campaign. In appendices we also report on the performance of the corrected Vaisala RS92 radiosonde measurements during the campaign, on a new radiosonde based calibration algorithm that reduces the influence of atmospheric variability on the derived calibration constant, and on other results of the ALVICE deployment. The MOHAVE-2009 campaign permitted the Raman lidar systems participating to discover and address measurement biases in the upper troposphere and lower stratosphere. The ALVICE lidar system was found to possess a wet bias which was attributed to fluorescence of insect material that was deposited on the telescope early in the mission. Other sources of wet biases are discussed and data from other Raman lidar systems are investigated, revealing that wet biases in upper tropospheric (UT) and lower stratospheric (LS) water vapor measurements appear to be quite common in Raman lidar systems. Lower stratospheric climatology of water vapor is investigated both as a means to check for the existence of these wet biases in Raman lidar data and as a source of correction for the bias. A correction technique is derived and applied to the ALVICE lidar water vapor profiles. Good agreement is found between corrected ALVICE lidar measurments and those of RS92, frost point hygrometer and total column water. The correction is offered as a general method to both quality control Raman water vapor lidar data and to correct those data that have signal-dependent bias. The influence of the correction is shown to be small at regions in the upper troposphere where recent work indicates detection of trends in atmospheric water vapor may be most robust. The correction shown here holds promise for permitting useful upper

  19. Precision and bias of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1983; and January 1980 through September 1984

    USGS Publications Warehouse

    Schroder, L.J.; Bricker, A.W.; Willoughby, T.C.

    1985-01-01

    Blind-audit samples with known analyte concentrations have been prepared by the U.S. Geological Survey and distributed to the National Atmospheric Deposition Program 's Central Analytical Laboratory. The difference between the National Atmospheric Deposition Program and National Trends Network reported analyte concentrations and known analyte concentrations have been calculated, and the bias has been determined. Calcium, magnesium , sodium, and chloride were biased at the 99-percent confidence limit; potassium and sulfate were unbiased at the 99-percent confidence limit, for 1983 results. Relative-percent differences between the measured and known analyte concentration for calcium , magnesium, sodium, potassium, chloride, and sulfate have been calculated for 1983. The median relative percent difference for calcium was 17.0; magnesium was 6.4; sodium was 10.8; potassium was 6.4; chloride was 17.2; and sulfate was -5.3. These relative percent differences should be used to correct the 1983 data before user-analysis of the data. Variances have been calculated for calcium, magnesium, sodium, potassium, chloride, and sulfate determinations. These variances should be applicable to natural-sample analyte concentrations reported by the National Atmospheric Deposition Program and National Trends Network for calendar year 1983. (USGS)

  20. Observed trends in mental health: a strategy to adjust for nonresponse bias and demographic changes in survey data.

    PubMed

    Johansen, Rune; Rognerud, Marit; Sundet, Jon Martin; Aarø, Leif Edvard

    2012-11-01

    To examine whether observed changes in self-reported psychological distress symptoms reflect true changes in psychological distress in the population, or more specifically, to present statistical methods to check for nonresponse bias and demographic changes. Lack of representativity, nonresponse bias and demographic changes were controlled for by weighing of data (sample-balancing or raking). Controlling for age, gender and education, or holding the demographic structure constant over time, slightly weakened the decrease in psychological distress from 1998 to 2002, and left the changes in psychological distress from 2002 to 2008 almost unchanged. When the level of psychological distress was held constant across years in every subgroup defined by age, gender and education, in order to isolate the effects of changes in demography, the distress scores showed only minor variation across data collection occasions from 1998 to 2008. The observed modest decrease in psychological distress from 1998 to 2002 may partly be explained by selection and demographic changes, while this is not the case with the more pronounced changes from 2002 to 2008.

  1. Bias in research.

    PubMed

    Simundić, Ana-Maria

    2013-01-01

    By writing scientific articles we communicate science among colleagues and peers. By doing this, it is our responsibility to adhere to some basic principles like transparency and accuracy. Authors, journal editors and reviewers need to be concerned about the quality of the work submitted for publication and ensure that only studies which have been designed, conducted and reported in a transparent way, honestly and without any deviation from the truth get to be published. Any such trend or deviation from the truth in data collection, analysis, interpretation and publication is called bias. Bias in research can occur either intentionally or unintentionally. Bias causes false conclusions and is potentially misleading. Therefore, it is immoral and unethical to conduct biased research. Every scientist should thus be aware of all potential sources of bias and undertake all possible actions to reduce or minimize the deviation from the truth. This article describes some basic issues related to bias in research.

  2. Within-person study designs had lower precision and greater susceptibility to bias because of trends in exposure than cohort and nested case-control designs.

    PubMed

    Nicholas, Jennifer M; Grieve, Andrew P; Gulliford, Martin C

    2012-04-01

    To compare precision and apparent bias between cohort, nested case-control, self-controlled case series, case-crossover, and case-time-control study designs. Study designs were implemented to evaluate the association between thiazolidinediones (TZDs) and heart failure, TZDs and fracture, and liver enzyme-inducing anticonvulsants and fracture. Effect estimates were similar for the cohort and case-control study; for the association between TZDs and fracture in women, the hazard ratio was 1.36 (1.18, 1.56) and odds ratio (OR) was 1.44 (1.21, 1.70). For this clinical example, the self-controlled case series gave upward bias when follow-up was censored at the outcome (incidence rate ratio [IRR], 7.08; 4.96, 10.09) but was otherwise unbiased (IRR, 1.41; 1.14, 1.75). The retrospective case-crossover OR was 3.24 (2.18, 4.80), which was reduced by either bidirectional sampling (OR, 1.20; 0.98, 1.46) or with the case-time-control design (OR, 1.40; 1.09, 1.81). Findings on apparent bias were similar for the other two clinical examples. In each clinical example, within-person designs had considerably lower precision than the cohort or case-control study designs. When long-term exposures are analyzed, within-person study designs may have lower precision and greater susceptibility to bias. Bias may be reduced by sampling follow-up both before and after the outcome or with the case-time-control study design. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Eliminating Bias

    EPA Pesticide Factsheets

    Learn how to eliminate bias from monitoring systems by instituting appropriate installation, operation, and quality assurance procedures. Provides links to download An Operator's Guide to Eliminating Bias in CEM Systems.

  4. Intergroup bias.

    PubMed

    Hewstone, Miles; Rubin, Mark; Willis, Hazel

    2002-01-01

    This chapter reviews the extensive literature on bias in favor of in-groups at the expense of out-groups. We focus on five issues and identify areas for future research: (a) measurement and conceptual issues (especially in-group favoritism vs. out-group derogation, and explicit vs. implicit measures of bias); (b) modern theories of bias highlighting motivational explanations (social identity, optimal distinctiveness, uncertainty reduction, social dominance, terror management); (c) key moderators of bias, especially those that exacerbate bias (identification, group size, status and power, threat, positive-negative asymmetry, personality and individual differences); (d) reduction of bias (individual vs. intergroup approaches, especially models of social categorization); and (e) the link between intergroup bias and more corrosive forms of social hostility.

  5. Invited commentary: Can changes in the distributions of and associations between education and income bias estimates of temporal trends in health disparities?

    PubMed

    Talih, Makram

    2013-05-01

    Chen et al. (Am J Epidemiol. 2013;177(9):870-881) develop a simulation study for comparing various measures of socioeconomic health disparities when bias can arise from temporal changes in the bivariate distribution of education and income. In this commentary, I argue that, in relation to health, the "meaning" of education cannot be reduced to its socioeconomic value; improved health literacy, for instance, can result in important health benefits. Further, I suggest that unless there is a substantial prior understanding of the data-generating mechanism, directed acyclic graph models should be avoided because causal relationships cannot be inferred from regression. An alternative is to resort to conditional independence graphs, which use only undirected edges. Finally, although the slope index of inequality can, in some specific cases, be seen to reduce bias in temporal comparisons of socioeconomic health disparities, it was not designed for causal inference. The slope index of inequality simply describes the average change in the proportion in poor health when the population is ordered by socioeconomic status.

  6. Contributions to the mammalogy of Chile

    USGS Publications Warehouse

    Pine, Ronald H.; Miller, Sterling D.; Schamberger, Mel L.

    1979-01-01

    Collections of mammals were made during more than three years of biological investigations in Chile sponsored by the Corporación Nacional Forestal under the aegis of the Peace Corps (Smithsonian Environmental Program). Genera and species hitherto unreported for that country were taken and many useful data concerning distributional patterns of other (mostly little-known) species were gathered. These collections have also proved valuable in better understanding Chilean mammals from a taxonomic point of view and contribute knowledge of the species' natural history. Specimens are to be deposited in the (United States) National Museum of Natural History (USNM) or are to be retained by the Corporación Nacional Forestal, Avda, Bulnes 285, Depto. 401, Santiago. Numbers provided below are field numbers. A final division of specimens between the two institutions has not yet been made. A number of specimens reported here were not taken by Peace Corps personnel but have been obtained by the National Museum of Natural History from other sources. Specimens in the Field Museum of Natural History (FMNH) were used in making comparisons. Some of Fulk's (GWF) specimens are at Texas Tech University. Other are at the Servicio Agricola y Ganadero in Santiago (as are specimens of some introduced species taken by Schamberger). Reise's (DF) are at the Universidad de Chile-Concepción and in his personal collection.

  7. Journal bias or author bias?

    PubMed

    Harris, Ian

    2016-01-01

    I read with interest the comment by Mark Wilson in the Indian Journal of Medical Ethics regarding bias and conflicts of interest in medical journals. Wilson targets one journal (the New England Journal of Medicine: NEJM) and one particular "scandal" to make his point that journals' decisions on publication are biased by commercial conflicts of interest (CoIs). It is interesting that he chooses the NEJM which, by his own admission, had one of the strictest CoI policies and had published widely on this topic. The feeling is that if the NEJM can be guilty, they can all be guilty.

  8. The Trend-in-trend Research Design for Causal Inference.

    PubMed

    Ji, Xinyao; Small, Dylan S; Leonard, Charles E; Hennessy, Sean

    2017-07-01

    Cohort studies can be biased by unmeasured confounding. We propose a hybrid ecologic-epidemiologic design called the trend-in-trend design, which requires a strong time trend in exposure, but is unbiased unless there are unmeasured factors affecting outcome for which there are time trends in prevalence that are correlated with time trends in exposure across strata with different exposure trends. Thus, the conditions under which the trend-in-trend study is biased are a subset of those under which a cohort study is biased. The trend-in-trend design first divides the study population into strata based on the cumulative probability of exposure given covariates, which effectively stratifies on time trend in exposure, provided there is a trend. Next, a covariates-free maximum likelihood model estimates the odds ratio (OR) using data on exposure prevalence and outcome frequency within cumulative probability of exposure strata, across multiple periods. In simulations, the trend-in-trend design produced ORs with negligible bias in the presence of unmeasured confounding. In empiric applications, trend-in-trend reproduced the known positive association between rofecoxib and myocardial infarction (observed OR: 1.2, 95% confidence interval: 1.1, 1.4), and known null associations between rofecoxib and severe hypoglycemia (OR = 1.1 [0.92, 1.3]) and nonvertebral fracture (OR = 0.84 [0.64, 1.1]). The trend-in-trend method may be useful in settings where there is a strong time trend in exposure, such as a newly approved drug or other medical intervention. See video abstract at, http://links.lww.com/EDE/B178.

  9. The Trend-in-trend Research Design for Causal Inference

    PubMed Central

    Ji, Xinyao; Small, Dylan S.; Leonard, Charles E.

    2017-01-01

    Cohort studies can be biased by unmeasured confounding. We propose a hybrid ecologic-epidemiologic design called the trend-in-trend design, which requires a strong time trend in exposure, but is unbiased unless there are unmeasured factors affecting outcome for which there are time trends in prevalence that are correlated with time trends in exposure across strata with different exposure trends. Thus, the conditions under which the trend-in-trend study is biased are a subset of those under which a cohort study is biased. The trend-in-trend design first divides the study population into strata based on the cumulative probability of exposure given covariates, which effectively stratifies on time trend in exposure, provided there is a trend. Next, a covariates-free maximum likelihood model estimates the odds ratio (OR) using data on exposure prevalence and outcome frequency within cumulative probability of exposure strata, across multiple periods. In simulations, the trend-in-trend design produced ORs with negligible bias in the presence of unmeasured confounding. In empiric applications, trend-in-trend reproduced the known positive association between rofecoxib and myocardial infarction (observed OR: 1.2, 95% confidence interval: 1.1, 1.4), and known null associations between rofecoxib and severe hypoglycemia (OR = 1.1 [0.92, 1.3]) and nonvertebral fracture (OR = 0.84 [0.64, 1.1]). The trend-in-trend method may be useful in settings where there is a strong time trend in exposure, such as a newly approved drug or other medical intervention. See video abstract at, http://links.lww.com/EDE/B178. PMID:27775954

  10. Observational biases for transiting planets

    NASA Astrophysics Data System (ADS)

    Kipping, David M.; Sandford, Emily

    2016-12-01

    Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 au of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.

  11. Berkson's bias, selection bias, and missing data.

    PubMed

    Westreich, Daniel

    2012-01-01

    Although Berkson's bias is widely recognized in the epidemiologic literature, it remains underappreciated as a model of both selection bias and bias due to missing data. Simple causal diagrams and 2 × 2 tables illustrate how Berkson's bias connects to collider bias and selection bias more generally, and show the strong analogies between Berksonian selection bias and bias due to missing data. In some situations, considerations of whether data are missing at random or missing not at random are less important than the causal structure of the missing data process. Although dealing with missing data always relies on strong assumptions about unobserved variables, the intuitions built with simple examples can provide a better understanding of approaches to missing data in real-world situations.

  12. Halo assembly bias from Separate Universe simulations

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem; Padmanabhan, Nikhil

    2017-07-01

    We present a calibration of halo assembly bias using the Separate Universe technique. Specifically, we measure the response of halo abundances at fixed mass and concentration to the presence of an infinite-wavelength initial perturbation. We develop an analytical framework for describing the concentration dependence of this peak-background split halo bias - a measure of assembly bias - relying on the near-lognormal distribution of halo concentration at fixed halo mass. The combination of this analytical framework and the Separate Universe technique allows us to achieve very high precision in the calibration of the linear assembly bias b1, and qualitatively reproduces known trends such as the monotonic decrease (increase) of b1 with halo concentration at large (small) masses. The same framework extends to the concentration dependence of higher order bias parameters bn, and we present the first calibration of assembly bias in b2. Our calibrations are directly applicable in analytical Halo Model calculations that seek to robustly detect galaxy assembly bias in observational samples. We detect a non-universality in the b1-b2 relation arising from assembly bias, and suggest that simultaneous measurements of these bias parameters could be used to both detect the signature of assembly bias as well as mitigate its effects in cosmological analyses.

  13. The Likelihood of Injury Among Bias Crimes: An Analysis of General and Specific Bias Types.

    PubMed

    Pezzella, Frank S; Fetzer, Matthew D

    2015-06-18

    In 2009, President Barack Obama signed the Mathew Sheppard and James Byrd Jr. Hate Crimes Protection act and thereby extended the list of previously protected classes of victims from actual or perceived race, color, religion, national origin, disability and sex orientation to gender and gender identity. Over 45 states, the District of Columbia and the federal government now include hate crime statutes that increase penalties when offenders perpetrate hate crimes against protected classes of victims. Penalty enhancement statutes sanction unlawful bias conduct arguably because they result in more severe injuries relative to non-bias conduct. We contend that physical injuries vary by bias type and are not equally injurious. Data on bias crimes was analyzed from the National Incident Based Reporting System. Descriptive patterns of bias crimes were identified by offense type, bias motivation and major and minor injuries. Using Multivariate analyses, we found an escalating trend of violence against racial minorities. Moreover, relative to non-bias crimes, only anti-White and anti-lesbian bias crimes experienced our two prong "animus" criteria of disproportionate prevalence and severity of injury. However, when compared to anti-White bias, anti-Black bias crimes were more prevalent and likely to suffer serious injuries. Implications for hate crime jurisprudence are discussed.

  14. Recalibrating Academic Bias

    ERIC Educational Resources Information Center

    Yancey, George

    2012-01-01

    Whether political and/or religious academic bias exists is a question with important ramifications for the educational institutions. Those arguing for the presence of such bias contend that political conservatives and the highly religious in academia are marginalized and face discrimination. The question of academic bias tends to be cast in a…

  15. Oaths and hypothetical bias.

    PubMed

    Stevens, T H; Tabatabaei, Maryam; Lass, Daniel

    2013-09-30

    Results from experiments using an oath to eliminate hypothetical bias in stated preference valuation are presented. An oath has several potential advantages relative to other methods for reducing hypothetical bias. Our empirical results suggest that with an oath, mean hypothetical payments are not different from mean actual payments and that when controlling for experimental participants' characteristics using regression analyses, the oath eliminated hypothetical bias.

  16. Demonstrating the Correspondence Bias

    ERIC Educational Resources Information Center

    Howell, Jennifer L.; Shepperd, James A.

    2011-01-01

    Among the best-known and most robust biases in person perception is the correspondence bias--the tendency for people to make dispositional, rather than situational, attributions for an actor's behavior. The correspondence bias appears in virtually every social psychology textbook and in many introductory psychology textbooks, yet the authors'…

  17. Demonstrating the Correspondence Bias

    ERIC Educational Resources Information Center

    Howell, Jennifer L.; Shepperd, James A.

    2011-01-01

    Among the best-known and most robust biases in person perception is the correspondence bias--the tendency for people to make dispositional, rather than situational, attributions for an actor's behavior. The correspondence bias appears in virtually every social psychology textbook and in many introductory psychology textbooks, yet the authors'…

  18. Queries for Bias Testing

    NASA Technical Reports Server (NTRS)

    Gordon, Diana F.

    1992-01-01

    Selecting a good bias prior to concept learning can be difficult. Therefore, dynamic bias adjustment is becoming increasingly popular. Current dynamic bias adjustment systems, however, are limited in their ability to identify erroneous assumptions about the relationship between the bias and the target concept. Without proper diagnosis, it is difficult to identify and then remedy faulty assumptions. We have developed an approach that makes these assumptions explicit, actively tests them with queries to an oracle, and adjusts the bias based on the test results.

  19. Renormalized halo bias

    SciTech Connect

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; Zaldarriaga, Matias E-mail: dbaumann@damtp.cam.ac.uk E-mail: matiasz@ias.edu

    2014-08-01

    This paper provides a systematic study of renormalization in models of halo biasing. Building on work of McDonald, we show that Eulerian biasing is only consistent with renormalization if non-local terms and higher-derivative contributions are included in the biasing model. We explicitly determine the complete list of required bias parameters for Gaussian initial conditions, up to quartic order in the dark matter density contrast and at leading order in derivatives. At quadratic order, this means including the gravitational tidal tensor, while at cubic order the velocity potential appears as an independent degree of freedom. Our study naturally leads to an effective theory of biasing in which the halo density is written as a double expansion in fluctuations and spatial derivatives. We show that the bias expansion can be organized in terms of Galileon operators which aren't renormalized at leading order in derivatives. Finally, we discuss how the renormalized bias parameters impact the statistics of halos.

  20. "Catching" Social Bias.

    PubMed

    Skinner, Allison L; Meltzoff, Andrew N; Olson, Kristina R

    2017-02-01

    Identifying the origins of social bias is critical to devising strategies to overcome prejudice. In two experiments, we tested the hypothesis that young children can catch novel social biases from brief exposure to biased nonverbal signals demonstrated by adults. Our results are consistent with this hypothesis. In Experiment 1, we found that children who were exposed to a brief video depicting nonverbal bias in favor of one individual over another subsequently explicitly preferred, and were more prone to behave prosocially toward, the target of positive nonverbal signals. Moreover, in Experiment 2, preschoolers generalized such bias to other individuals. The spread of bias observed in these experiments lays a critical foundation for understanding the way that social biases may develop and spread early in childhood.

  1. Bias in clinical chemistry.

    PubMed

    Theodorsson, Elvar; Magnusson, Bertil; Leito, Ivo

    2014-01-01

    Clinical chemistry uses automated measurement techniques and medical knowledge in the interest of patients and healthy subjects. Automation has reduced repeatability and day-to-day variation considerably. Bias has been reduced to a lesser extent by reference measurement systems. It is vital to minimize clinically important bias, in particular bias within conglomerates of laboratories that measure samples from the same patients. Small and variable bias components will over time show random error properties and conventional random-error based methods for calculating measurement uncertainty can then be applied. The present overview of bias presents the general principles of error and uncertainty concepts, terminology and analysis, and suggests methods to minimize bias and measurement uncertainty in the interest of healthcare.

  2. Interpretation biases in paranoia.

    PubMed

    Savulich, George; Freeman, Daniel; Shergill, Sukhi; Yiend, Jenny

    2015-01-01

    Information in the environment is frequently ambiguous in meaning. Emotional ambiguity, such as the stare of a stranger, or the scream of a child, encompasses possible good or bad emotional consequences. Those with elevated vulnerability to affective disorders tend to interpret such material more negatively than those without, a phenomenon known as "negative interpretation bias." In this study we examined the relationship between vulnerability to psychosis, measured by trait paranoia, and interpretation bias. One set of material permitted broadly positive/negative (valenced) interpretations, while another allowed more or less paranoid interpretations, allowing us to also investigate the content specificity of interpretation biases associated with paranoia. Regression analyses (n=70) revealed that trait paranoia, trait anxiety, and cognitive inflexibility predicted paranoid interpretation bias, whereas trait anxiety and cognitive inflexibility predicted negative interpretation bias. In a group comparison those with high levels of trait paranoia were negatively biased in their interpretations of ambiguous information relative to those with low trait paranoia, and this effect was most pronounced for material directly related to paranoid concerns. Together these data suggest that a negative interpretation bias occurs in those with elevated vulnerability to paranoia, and that this bias may be strongest for material matching paranoid beliefs. We conclude that content-specific biases may be important in the cause and maintenance of paranoid symptoms.

  3. Continuous Glucose Monitoring and Trend Accuracy

    PubMed Central

    Gottlieb, Rebecca; Le Compte, Aaron; Chase, J. Geoffrey

    2014-01-01

    Continuous glucose monitoring (CGM) devices are being increasingly used to monitor glycemia in people with diabetes. One advantage with CGM is the ability to monitor the trend of sensor glucose (SG) over time. However, there are few metrics available for assessing the trend accuracy of CGM devices. The aim of this study was to develop an easy to interpret tool for assessing trend accuracy of CGM data. SG data from CGM were compared to hourly blood glucose (BG) measurements and trend accuracy was quantified using the dot product. Trend accuracy results are displayed on the Trend Compass, which depicts trend accuracy as a function of BG. A trend performance table and Trend Index (TI) metric are also proposed. The Trend Compass was tested using simulated CGM data with varying levels of error and variability, as well as real clinical CGM data. The results show that the Trend Compass is an effective tool for differentiating good trend accuracy from poor trend accuracy, independent of glycemic variability. Furthermore, the real clinical data show that the Trend Compass assesses trend accuracy independent of point bias error. Finally, the importance of assessing trend accuracy as a function of BG level is highlighted in a case example of low and falling BG data, with corresponding rising SG data. This study developed a simple to use tool for quantifying trend accuracy. The resulting trend accuracy is easily interpreted on the Trend Compass plot, and if required, performance table and TI metric. PMID:24876437

  4. The Bias Fallacy

    ERIC Educational Resources Information Center

    Linvill, Darren L.

    2013-01-01

    Do those who complain about liberal bias in higher education have any actionable point at all? Critics of the politicization of higher education claim that political partisanship in the classroom is pervasive and that it affects student learning. Although the existence of such partisanship has not been empirically proven, allegations of bias are…

  5. Biased predecision processing.

    PubMed

    Brownstein, Aaron L

    2003-07-01

    Decision makers conduct biased predecision processing when they restructure their mental representation of the decision environment to favor one alternative before making their choice. The question of whether biased predecision processing occurs has been controversial since L. Festinger (1957) maintained that it does not occur. The author reviews relevant research in sections on theories of cognitive dissonance, decision conflict, choice certainty, action control, action phases, dominance structuring, differentiation and consolidation, constructive processing, motivated reasoning, and groupthink. Some studies did not find evidence of biased predecision processing, but many did. In the Discussion section, the moderators are summarized and used to assess the theories.

  6. Introduction to Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Schmelz, Joan T.

    2010-05-01

    We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.

  7. Estimating Bias Error Distributions

    NASA Technical Reports Server (NTRS)

    Liu, Tian-Shu; Finley, Tom D.

    2001-01-01

    This paper formulates the general methodology for estimating the bias error distribution of a device in a measuring domain from less accurate measurements when a minimal number of standard values (typically two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution arc developed. These methods are virtually applicable to any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods have been validated through computational simulations and laboratory calibration experiments for a number of different devices.

  8. Increasingly minimal bias routing

    DOEpatents

    Bataineh, Abdulla; Court, Thomas; Roweth, Duncan

    2017-02-21

    A system and algorithm configured to generate diversity at the traffic source so that packets are uniformly distributed over all of the available paths, but to increase the likelihood of taking a minimal path with each hop the packet takes. This is achieved by configuring routing biases so as to prefer non-minimal paths at the injection point, but increasingly prefer minimal paths as the packet proceeds, referred to herein as Increasing Minimal Bias (IMB).

  9. Continuous glucose monitoring and trend accuracy: news about a trend compass.

    PubMed

    Signal, Matthew; Gottlieb, Rebecca; Le Compte, Aaron; Chase, J Geoffrey

    2014-09-01

    Continuous glucose monitoring (CGM) devices are being increasingly used to monitor glycemia in people with diabetes. One advantage with CGM is the ability to monitor the trend of sensor glucose (SG) over time. However, there are few metrics available for assessing the trend accuracy of CGM devices. The aim of this study was to develop an easy to interpret tool for assessing trend accuracy of CGM data. SG data from CGM were compared to hourly blood glucose (BG) measurements and trend accuracy was quantified using the dot product. Trend accuracy results are displayed on the Trend Compass, which depicts trend accuracy as a function of BG. A trend performance table and Trend Index (TI) metric are also proposed. The Trend Compass was tested using simulated CGM data with varying levels of error and variability, as well as real clinical CGM data. The results show that the Trend Compass is an effective tool for differentiating good trend accuracy from poor trend accuracy, independent of glycemic variability. Furthermore, the real clinical data show that the Trend Compass assesses trend accuracy independent of point bias error. Finally, the importance of assessing trend accuracy as a function of BG level is highlighted in a case example of low and falling BG data, with corresponding rising SG data. This study developed a simple to use tool for quantifying trend accuracy. The resulting trend accuracy is easily interpreted on the Trend Compass plot, and if required, performance table and TI metric. © 2014 Diabetes Technology Society.

  10. Instructional Time Trends. Education Trends

    ERIC Educational Resources Information Center

    Woods, Julie Rowland

    2015-01-01

    For more than 30 years, Education Commission of the States has tracked instructional time and frequently receives requests for information about policies and trends. In this Education Trends report, Education Commission of the States addresses some of the more frequent questions, including the impact of instructional time on achievement, variation…

  11. Characteristics of plasma grid bias in large-scaled negative ion source

    SciTech Connect

    Kisaki, M.; Tsumori, K.; Ikeda, K.; Nakano, H.; Osakabe, M.; Nagaoka, K.; Takeiri, Y.; Kaneko, O.

    2014-02-15

    The electron density was measured at various bias voltages to understand how the plasma grid bias affects the electron near the plasma grid in large-scaled negative ion sources. It was found that the response of the electron to the bias voltage changes depending on negative ion production processes. The electron density remarkably decreases with increasing the bias voltage in the pure-volume plasma. On the other hand, the electron density depends on the bias voltage weakly in the Cs-seeded plasma. In addition, it was observed that the response of the co-extracted electron current to the bias voltage has similar trend to that of the electron density.

  12. Program Trends.

    ERIC Educational Resources Information Center

    Moss, Jeffrey W.; And Others

    1989-01-01

    Articles by Moss, Van Huss, Raynor, Lynch, and Sullivan discuss the trends in all areas of vocational education. Includes information on how new technologies, life-styles, and job demands have changed or should change vocational education. (JOW)

  13. Observatory crustal magnetic biases during CHAMP satellite mission

    NASA Astrophysics Data System (ADS)

    Verbanac, G.; Mandea, M.; Bandić, M.; Subašić, S.

    2015-01-01

    Taking advantage of nine years of CHAMP satellite mission (June 2000-August 2009), we investigate the temporal evolution of the observatory monthly crustal magnetic biases. To determine biases we compute X (northward), Y (eastward) and Z (vertically downward) monthly means from 42 observatory one-minute or hourly values, and compare them to synthetic monthly means obtained from a GRIMM3 core field model (V. Lesur, personal communication, 2014). Both short period variations and long term trends in the monthly bias time series are analyzed. A comparison with biases based on MAGSAT and Ørsted satellite data, related to the 1979.92 and 1992.92 epochs is performed. Generally, the larger biases averaged over nine years and the larger differences between biases based on different models are found in Z component. This can be the signature of the induced magnetic fields. Although annual trends in most bias series are observed, no clear evidence that the constant crustal field changed significantly over the studied period is found. Time series of monthly biases exhibit distinct oscillatory pattern in the whole time span, which we assign to the external field contributions. The amplitudes of these variations are linked with the phase of the solar cycle, being significantly larger in the period 2000-2005 than in the period 2006-2009. Clear semi-annual variations are evident in all components, with extremes in spring and fall months of each year. Common external field pattern is found for European monthly biases. A dependence of the bias monthly variations on geomagnetic latitudes is not found for the non-European observatories. The results from this study represent a base to further exploit the observatory and repeat stations magnetic biases together with the data from the new satellite mission SWARM.

  14. Distinguishing Selection Bias and Confounding Bias in Comparative Effectiveness Research.

    PubMed

    Haneuse, Sebastien

    2016-04-01

    Comparative effectiveness research (CER) aims to provide patients and physicians with evidence-based guidance on treatment decisions. As researchers conduct CER they face myriad challenges. Although inadequate control of confounding is the most-often cited source of potential bias, selection bias that arises when patients are differentially excluded from analyses is a distinct phenomenon with distinct consequences: confounding bias compromises internal validity, whereas selection bias compromises external validity. Despite this distinction, however, the label "treatment-selection bias" is being used in the CER literature to denote the phenomenon of confounding bias. Motivated by an ongoing study of treatment choice for depression on weight change over time, this paper formally distinguishes selection and confounding bias in CER. By formally distinguishing selection and confounding bias, this paper clarifies important scientific, design, and analysis issues relevant to ensuring validity. First is that the 2 types of biases may arise simultaneously in any given study; even if confounding bias is completely controlled, a study may nevertheless suffer from selection bias so that the results are not generalizable to the patient population of interest. Second is that the statistical methods used to mitigate the 2 biases are themselves distinct; methods developed to control one type of bias should not be expected to address the other. Finally, the control of selection and confounding bias will often require distinct covariate information. Consequently, as researchers plan future studies of comparative effectiveness, care must be taken to ensure that all data elements relevant to both confounding and selection bias are collected.

  15. Reassessing biases and other uncertainties in sea surface temperature observations measured in situ since 1850: 2. Biases and homogenization

    NASA Astrophysics Data System (ADS)

    Kennedy, J. J.; Rayner, N. A.; Smith, R. O.; Parker, D. E.; Saunby, M.

    2011-07-01

    Changes in instrumentation and data availability have caused time-varying biases in estimates of global and regional average sea surface temperature. The size of the biases arising from these changes are estimated and their uncertainties evaluated. The estimated biases and their associated uncertainties are largest during the period immediately following the Second World War, reflecting the rapid and incompletely documented changes in shipping and data availability at the time. Adjustments have been applied to reduce these effects in gridded data sets of sea surface temperature and the results are presented as a set of interchangeable realizations. Uncertainties of estimated trends in global and regional average sea surface temperature due to bias adjustments since the Second World War are found to be larger than uncertainties arising from the choice of analysis technique, indicating that this is an important source of uncertainty in analyses of historical sea surface temperatures. Despite this, trends over the twentieth century remain qualitatively consistent.

  16. Optically biased laser gyro

    SciTech Connect

    Anderson, D.Z.; Chow, W.W.; Scully, M.O.; Sanders, V.E.

    1980-10-01

    We describe a four-mode ring laser that exhibits none of the mode-locking characteristics that plague laser gyros. This laser is characterized by a bias that changes sign with a change in the direction of rotation and prevents the counterpropagating modes from locking. A theoretical analysis explaining the experimental results is outlined.

  17. A significant bias

    NASA Astrophysics Data System (ADS)

    Eades, Alwyn

    2013-09-01

    While I do not wish to belittle the unfortunate conclusions that may be drawn from your news article "Gender bias judges research by women more critically" (May p12), I do want to comment on the way the article is presented.

  18. Sex Bias in Children.

    ERIC Educational Resources Information Center

    Zalk, Sue Rosenberg; And Others

    This study investigated children's sex biased attitudes as a function of the sex, age, and race of the child as well as a geographical-SES factor. Two attitudes were measured on a 55-item questionnaire: Sex Pride (attributing positive characteristics to a child of the same sex) and Sex Prejudice (attributing negative characteristics to a child of…

  19. Own Variety Bias

    PubMed Central

    García, Andrea Ariza

    2015-01-01

    In a language identification task, native Belgian French and native Swiss French speakers identified French from France as their own variety. However, Canadian French was not subject to this bias. Canadian and French listeners didn’t claim a different variety as their own. PMID:27648211

  20. Killer whales and marine mammal trends in the North Pacific - A re-examination of evidence for sequential megafauna collapse and the prey-switching hypothesis

    USGS Publications Warehouse

    Wade, P.R.; Burkanov, V.N.; Dahlheim, M.E.; Friday, N.A.; Fritz, L.W.; Loughlin, Thomas R.; Mizroch, S.A.; Muto, M.M.; Rice, D.W.; Barrett-Lennard, L. G.; Black, N.A.; Burdin, A.M.; Calambokidis, J.; Cerchio, S.; Ford, J.K.B.; Jacobsen, J.K.; Matkin, C.O.; Matkin, D.R.; Mehta, A.V.; Small, R.J.; Straley, J.M.; McCluskey, S.M.; VanBlaricom, G.R.; Clapham, P.J.

    2007-01-01

    Springer et al. (2003) contend that sequential declines occurred in North Pacific populations of harbor and fur seals, Steller sea lions, and sea otters. They hypothesize that these were due to increased predation by killer whales, when industrial whaling's removal of large whales as a supposed primary food source precipitated a prey switch. Using a regional approach, we reexamined whale catch data, killer whale predation observations, and the current biomass and trends of potential prey, and found little support for the prey-switching hypothesis. Large whale biomass in the Bering Sea did not decline as much as suggested by Springer et al., and much of the reduction occurred 50-100 yr ago, well before the declines of pinnipeds and sea otters began; thus, the need to switch prey starting in the 1970s is doubtful. With the sole exception that the sea otter decline followed the decline of pinnipeds, the reported declines were not in fact sequential. Given this, it is unlikely that a sequential megafaunal collapse from whales to sea otters occurred. The spatial and temporal patterns of pinniped and sea otter population trends are more complex than Springer et al. suggest, and are often inconsistent with their hypothesis. Populations remained stable or increased in many areas, despite extensive historical whaling and high killer whale abundance. Furthermore, observed killer whale predation has largely involved pinnipeds and small cetaceans; there is little evidence that large whales were ever a major prey item in high latitudes. Small cetaceans (ignored by Springer et al.) were likely abundant throughout the period. Overall, we suggest that the Springer et al. hypothesis represents a misleading and simplistic view of events and trophic relationships within this complex marine ecosystem. ?? 2007 by the Society for Marine Mammalogy.

  1. Berkson’s bias, selection bias, and missing data

    PubMed Central

    Westreich, Daniel

    2011-01-01

    While Berkson’s bias is widely recognized in the epidemiologic literature, it remains underappreciated as a model of both selection bias and bias due to missing data. Simple causal diagrams and 2×2 tables illustrate how Berkson’s bias connects to collider bias and selection bias more generally, and show the strong analogies between Berksonian selection bias and bias due to missing data. In some situations, considerations of whether data are missing at random or missing not at random is less important than the causal structure of the missing-data process. While dealing with missing data always relies on strong assumptions about unobserved variables, the intuitions built with simple examples can provide a better understanding of approaches to missing data in real-world situations. PMID:22081062

  2. Food Trends.

    ERIC Educational Resources Information Center

    Schwenk, Nancy E.

    1991-01-01

    An overall perspective on trends in food consumption is presented. Nutrition awareness is at an all-time high; consumption is influenced by changes in disposable income, availability of convenience foods, smaller household size, and an increasing proportion of ethnic minorities in the population. (18 references) (LB)

  3. Skiing trends

    Treesearch

    Charles R. Goeldner; Stacy Standley

    1980-01-01

    A brief historical overview of skiing is presented, followed by a review of factors such as energy, population trends, income, sex, occupation and attitudes which affect the future of skiing. A. C. Neilson's Sports Participation Surveys show that skiing is the second fastest growing sport in the country. Skiing Magazine's study indicates there are...

  4. Environmental Trends.

    ERIC Educational Resources Information Center

    Council on Environmental Quality, Washington, DC.

    This document consists of data which highlight trends in all sectors relevant to environmental policy. These data are presented in the form of charts and maps contained in 13 sections under the following headings: people and the land; critical areas (wetlands, wild areas, parks, historic places, and risk zones); human settlements; transportation;…

  5. A Ku-band laboratory experiment on the electromagnetic bias

    SciTech Connect

    Branger, H.; Ramamonjiarisoa, A.; Bliven, L.F.

    1993-11-01

    Sea-surface electromagnetic bias (EM bias), the difference between the mean reflecting surface and the geometric mean sea level, must be accurately determined to realize the full potential of satellite altimeters. A uniformly valid algorithm relating the normalized (or nondimensional) EM bias, i.e., ``bias/significant wave height,`` to physical variables has not yet been established, so the authors conducted laboratory experiments to guide model development. Dimensional relations seldom yield robust algorithms and in fact, although rather high correlation is found between normalized EM bias and either wind speed or wave height, the laboratory coefficients are considerably greater than those of in situ algorithms. Nondimensional parameterization is more useful for deriving scaling laws, and when the normalized EM bias is displayed as a function of wave height skewness or wave age, laboratory and field data converge into consistent trends. In particular, normalized bias decreases with wave age, but unfortunately, even the wave age model does not account for the effects of mechanically generated waves, which produce appreciable scatter relative to the pure wind cases. Thus, they propose a two-parameter model using (1) a nondimensional wave height, which is computed for local winds, and (2) a significant slope, which is computed for nonlocally generated waves. Analysis of the laboratory data shows that the normalized EM bias for mixed conditions is well modeled as a product of these two parameters.

  6. Global trends

    NASA Technical Reports Server (NTRS)

    Megie, G.; Chanin, M.-L.; Ehhalt, D.; Fraser, P.; Frederick, J. F.; Gille, J. C.; Mccormick, M. P.; Schoebert, M.; Bishop, L.; Bojkov, R. D.

    1990-01-01

    Measuring trends in ozone, and most other geophysical variables, requires that a small systematic change with time be determined from signals that have large periodic and aperiodic variations. Their time scales range from the day-to-day changes due to atmospheric motions through seasonal and annual variations to 11 year cycles resulting from changes in the sun UV output. Because of the magnitude of all of these variations is not well known and highly variable, it is necessary to measure over more than one period of the variations to remove their effects. This means that at least 2 or more times the 11 year sunspot cycle. Thus, the first requirement is for a long term data record. The second related requirement is that the record be consistent. A third requirement is for reasonable global sampling, to ensure that the effects are representative of the entire Earth. The various observational methods relevant to trend detection are reviewed to characterize their quality and time and space coverage. Available data are then examined for long term trends or recent changes in ozone total content and vertical distribution, as well as related parameters such as stratospheric temperature, source gases and aerosols.

  7. Distinguishing selection bias and confounding bias in comparative effectiveness research

    PubMed Central

    Haneuse, Sebastien

    2014-01-01

    Comparative effectiveness research (CER) aims to provide patients and physicians with evidence-based guidance on treatment decisions. As researchers conduct CER they face myriad challenges. While inadequate control of confounding is the most-often cited source of potential bias, selection bias which arises when patients are differentially excluded from analyses is a distinct phenomenon with distinct consequences: confounding bias compromises internal validity while selection bias compromises external validity. Despite this distinction, however, the label “treatment-selection bias” is being used in the CER literature to denote the phenomenon of confounding bias. Motivated by an on-going study of treatment choice for depression on weight change over time, we formally distinguish confounding and selection bias in CER. By formally distinguishing selection and confounding bias we clarify important scientific, design and analysis issues relevant to ensuring validity. First is that the two types of bias may arise simultaneously in any given study; even if confounding bias is completely controlled, a study may nevertheless suffer from selection bias so that the results are not generalizable to the patient population of interest. Second is that statistical methods used to mitigate the two biases are themselves distinct; methods developed to control one type of bias should not be expected to address the other. Finally, the control of selection and confounding bias will often require distinct covariate information. Consequently, as researchers plan future studies of comparative effectiveness, care must be taken to ensure that all data elements relevant to both confounding and selection bias are collected. PMID:24309675

  8. Effect of switched-bias bakes on the postirradiation electrical response of MOS devices

    SciTech Connect

    Fleetwood, D.M.; Shaneyfelt, M.R.; Riewe, L.C.; Winokur, P.S.

    1993-01-01

    Qualitatively different trends in postirradiation electrical response are observed in MOS devices after very long (up to 2.75-year) switched-bias bakes. A revised defect nomenclature is introduced, and implications for MOS defect models are discussed.

  9. Effect of switched-bias bakes on the postirradiation electrical response of MOS devices

    SciTech Connect

    Fleetwood, D.M.; Shaneyfelt, M.R.; Riewe, L.C.; Winokur, P.S.

    1993-03-01

    Qualitatively different trends in postirradiation electrical response are observed in MOS devices after very long (up to 2.75-year) switched-bias bakes. A revised defect nomenclature is introduced, and implications for MOS defect models are discussed.

  10. Biasing GPCR signaling from inside.

    PubMed

    Shukla, Arun K

    2014-01-28

    The discovery of "functional selectivity" or "biased signaling" through G protein-coupled receptors (GPCRs) has redefined the classical GPCR signaling paradigm. Moreover, the therapeutic potential of biased signaling by and biased ligands for GPCRs is changing the landscape of GPCR drug discovery. The concept of biased signaling has primarily been developed and discussed in the context of ligands that bind to the extracellular regions of GPCRs. However, two recent reports demonstrate that it is also possible to bias GPCR signaling from inside the cell by targeting intracellular regions of these receptors. These findings present a novel handle for delineating the functional outcomes of biased signaling by GPCRs. Moreover, these approaches also uncover a previously unexplored framework for biasing GPCR signaling for drug discovery.

  11. Evaluating solutions to sponsorship bias.

    PubMed

    Doucet, M; Sismondo, S

    2008-08-01

    More than 40 primary studies, and three recent systematic reviews and meta-analyses, have shown a clear association between pharmaceutical industry funding of clinical trials and pro-industry results. Industry sponsorship biases published scientific research in favour of the sponsors, a result of the strong interest commercial sponsors have in obtaining favourable results. Three proposed remedies to this problem are widely agreed upon among those concerned with the level of sponsorship bias: financial disclosure, reporting standards and trial registries. This paper argues that all of these remedies either fail to address the mechanisms by which pharmaceutical companies' sponsorship leads to biased results-design bias, multiple trials with predictable outcomes, fraud, rhetorical effects and publication bias-or else only inadequately address those mechanisms. As a result, the policies normally proposed for dealing with sponsorship bias are unable to eliminate it. Only completely separating public clinical research from pharmaceutical industry funding can eliminate sponsorship bias.

  12. Evaluation of trends in wheat yield models

    NASA Technical Reports Server (NTRS)

    Ferguson, M. C.

    1982-01-01

    Trend terms in models for wheat yield in the U.S. Great Plains for the years 1932 to 1976 are evaluated. The subset of meteorological variables yielding the largest adjusted R(2) is selected using the method of leaps and bounds. Latent root regression is used to eliminate multicollinearities, and generalized ridge regression is used to introduce bias to provide stability in the data matrix. The regression model used provides for two trends in each of two models: a dependent model in which the trend line is piece-wise continuous, and an independent model in which the trend line is discontinuous at the year of the slope change. It was found that the trend lines best describing the wheat yields consisted of combinations of increasing, decreasing, and constant trend: four combinations for the dependent model and seven for the independent model.

  13. Editorial bias in scientific publications.

    PubMed

    Matías-Guiu, J; García-Ramos, R

    2011-01-01

    Many authors believe that there are biases in scientific publications. Editorial biases include publication bias; which refers to those situations where the results influence the editor's decision, and editorial bias refers to those situations where factors related with authors or their environment influence the decision. This paper includes an analysis of the situation of editorial biases. One bias is where mainly articles with positive results are accepted, as opposed to those with negative results. Another is latent bias, where positive results are published before those with negative results. In order to examine editorial bias, this paper analyses the influence of where the article originated; the country or continent, academic centre of origin, belonging to cooperative groups, and the maternal language of the authors. The article analyses biases in the editorial process in the publication of funded clinical trials. Editorial biases exists. Authors, when submitting their manuscript, should analyse different journals and decide where their article will receive adequate treatment. Copyright © 2010 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  14. Sequential biases in accumulating evidence.

    PubMed

    Kulinskaya, Elena; Huggins, Richard; Dogo, Samson Henry

    2016-09-01

    Whilst it is common in clinical trials to use the results of tests at one phase to decide whether to continue to the next phase and to subsequently design the next phase, we show that this can lead to biased results in evidence synthesis. Two new kinds of bias associated with accumulating evidence, termed 'sequential decision bias' and 'sequential design bias', are identified. Both kinds of bias are the result of making decisions on the usefulness of a new study, or its design, based on the previous studies. Sequential decision bias is determined by the correlation between the value of the current estimated effect and the probability of conducting an additional study. Sequential design bias arises from using the estimated value instead of the clinically relevant value of an effect in sample size calculations. We considered both the fixed-effect and the random-effects models of meta-analysis and demonstrated analytically and by simulations that in both settings the problems due to sequential biases are apparent. According to our simulations, the sequential biases increase with increased heterogeneity. Minimisation of sequential biases arises as a new and important research area necessary for successful evidence-based approaches to the development of science. © 2015 The Authors. Research Synthesis Methods Published by John Wiley & Sons Ltd. © 2015 The Authors. Research Synthesis Methods Published by John Wiley & Sons Ltd.

  15. Assembly bias and splashback in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Busch, Philipp; White, Simon D. M.

    2017-10-01

    We use publicly available data for the Millennium Simulation to explore the implications of the recent detection of assembly bias and splashback signatures in a large sample of galaxy clusters. These were identified in the Sloan Digital Sky Survey/Data Release 8 (SDSS/DR8) photometric data by the redMaPPer algorithm and split into high- and low-concentration subsamples based on the projected positions of cluster members. We use simplified versions of these procedures to build cluster samples of similar size from the simulation data. These match the observed samples quite well and show similar assembly bias and splashback signals. Previous theoretical work has found the logarithmic slope of halo density profiles to have a well-defined minimum whose depth decreases and whose radius increases with halo concentration. Projected profiles for the observed and simulated cluster samples show trends with concentration which are opposite to these predictions. In addition, for high-concentration clusters the minimum slope occurs at significantly smaller radius than predicted. We show that these discrepancies all reflect confusion between splashback features and features imposed on the profiles by the cluster identification and concentration estimation procedures. The strong apparent assembly bias is not reflected in the three-dimensional distribution of matter around clusters. Rather it is a consequence of the preferential contamination of low-concentration clusters by foreground or background groups.

  16. Bias modification training can alter approach bias and chocolate consumption.

    PubMed

    Schumacher, Sophie E; Kemps, Eva; Tiggemann, Marika

    2016-01-01

    Recent evidence has demonstrated that bias modification training has potential to reduce cognitive biases for attractive targets and affect health behaviours. The present study investigated whether cognitive bias modification training could be applied to reduce approach bias for chocolate and affect subsequent chocolate consumption. A sample of 120 women (18-27 years) were randomly assigned to an approach-chocolate condition or avoid-chocolate condition, in which they were trained to approach or avoid pictorial chocolate stimuli, respectively. Training had the predicted effect on approach bias, such that participants trained to approach chocolate demonstrated an increased approach bias to chocolate stimuli whereas participants trained to avoid such stimuli showed a reduced bias. Further, participants trained to avoid chocolate ate significantly less of a chocolate muffin in a subsequent taste test than participants trained to approach chocolate. Theoretically, results provide support for the dual process model's conceptualisation of consumption as being driven by implicit processes such as approach bias. In practice, approach bias modification may be a useful component of interventions designed to curb the consumption of unhealthy foods. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Outcome predictability biases learning.

    PubMed

    Griffiths, Oren; Mitchell, Chris J; Bethmont, Anna; Lovibond, Peter F

    2015-01-01

    Much of contemporary associative learning research is focused on understanding how and when the associative history of cues affects later learning about those cues. Very little work has investigated the effects of the associative history of outcomes on human learning. Three experiments extended the "learned irrelevance" paradigm from the animal conditioning literature to examine the influence of an outcome's prior predictability on subsequent learning of relationships between cues and that outcome. All 3 experiments found evidence for the idea that learning is biased by the prior predictability of the outcome. Previously predictable outcomes were readily associated with novel predictive cues, whereas previously unpredictable outcomes were more readily associated with novel nonpredictive cues. This finding highlights the importance of considering the associative history of outcomes, as well as cues, when interpreting multistage designs. Associative and cognitive explanations of this certainty matching effect are discussed.

  18. The intentionality bias and schizotypy.

    PubMed

    Moore, J W; Pope, A

    2014-01-01

    The "intentionality bias" refers to our automatic tendency to judge other people's actions to be intentional. In this experiment we extended research on this effect in two key ways. First, we developed a novel nonlinguistic task for assessing the intentionality bias. This task used video stimuli of ambiguous movements. Second, we investigated the relationship between the strength of this bias and schizotypy (schizophrenia-like symptoms in healthy individuals). Our results showed that the intentionality bias was replicated for the video stimuli and also that this bias is stronger in those individuals scoring higher on the schizotypy rating scales. Overall these findings lend further support for the existence of the intentionality bias. We also discuss the possible relevance of these findings for our understanding of certain symptoms of schizophrenic illness.

  19. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-01-01

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  20. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-12-31

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  1. Size Bias in Galaxy Surveys

    NASA Astrophysics Data System (ADS)

    Schmidt, Fabian; Rozo, Eduardo; Dodelson, Scott; Hui, Lam; Sheldon, Erin

    2009-07-01

    Only certain galaxies are included in surveys: those bright and large enough to be detectable as extended sources. Because gravitational lensing can make galaxies appear both brighter and larger, the presence of foreground inhomogeneities can scatter galaxies across not only magnitude cuts but also size cuts, changing the statistical properties of the resulting catalog. Here we explore this size bias and how it combines with magnification bias to affect galaxy statistics. We demonstrate that photometric galaxy samples from current and upcoming surveys can be even more affected by size bias than by magnification bias.

  2. Social-Cognitive Bias and Depressive Symptoms in Outpatients with Bipolar Disorder

    PubMed Central

    Lahera, Guillermo; Benito, Adolfo; González-Barroso, Ana; Guardiola, Rocío; Herrera, Sara; Muchada, Beatriz; Cojedor, Noelia; Fernández-Liria, Alberto

    2012-01-01

    A deficit of social cognition in bipolar disorder has been shown, even when patients are stable. This study compares the attribution of intentions (social-cognitive bias) in a group of 37 outpatients with bipolar disorder with 32 matched control subjects. Bipolar patients scored significantly higher in the Ambiguous Intentions Hostility Questionnaire, showing an angry and intentionality bias (P = .001, P = .02). Differences in blame scale and hostility bias did not reach statistical significance, but a trend was found (P = .06). Bipolar patients with depressive symptoms presented a higher score in the angry bias scale (P = .03) and aggressivity bias scale (P = .004). The global functioning (GAF) correlates significantly with intentionality (P = .005), angry (P = .027), and aggressivity (P = .020) biases. Bipolar patients show a social-cognitive bias that may play a role in their functional outcome. PMID:22312485

  3. Summary of relationships between exchangeability, biasing paths and bias.

    PubMed

    Flanders, William Dana; Eldridge, Ronald Curtis

    2015-10-01

    Definitions and conceptualizations of confounding and selection bias have evolved over the past several decades. An important advance occurred with development of the concept of exchangeability. For example, if exchangeability holds, risks of disease in an unexposed group can be compared with risks in an exposed group to estimate causal effects. Another advance occurred with the use of causal graphs to summarize causal relationships and facilitate identification of causal patterns that likely indicate bias, including confounding and selection bias. While closely related, exchangeability is defined in the counterfactual-model framework and confounding paths in the causal-graph framework. Moreover, the precise relationships between these concepts have not been fully described. Here, we summarize definitions and current views of these concepts. We show how bias, exchangeability and biasing paths interrelate and provide justification for key results. For example, we show that absence of a biasing path implies exchangeability but that the reverse implication need not hold without an additional assumption, such as faithfulness. The close links shown are expected. However confounding, selection bias and exchangeability are basic concepts, so comprehensive summarization and definitive demonstration of links between them is important. Thus, this work facilitates and adds to our understanding of these important biases.

  4. Statistical biases in stellar astronomy: the Malmquist bias revisited

    NASA Astrophysics Data System (ADS)

    Butkevich, A. G.; Berdyugin, A. V.; Teerikorpi, P.

    2005-09-01

    A unified analytical treatment of the Malmquist bias is presented. Depending on the data under consideration and on the way the mean values of absolute magnitude are calculated, three different types of Malmquist bias appear: integral bias, and magnitude- and distance-dependent ones. An analytical consideration of the distance-dependent bias, previously studied in extragalactic astronomy, is given in terms of the trigonometric parallax. In a quantitative treatment of the Spaenhauer diagram, in which the derived absolute magnitude is plotted versus the true parallax, we developed an easy-to-use method for determination of the region unaffected by the bias (`unbiased plateau'). Considering spectroscopic distance indicators, we point out that for any magnitude-limited sample spectroscopic distance and parallax approach constant limits as the true distance increases. We draw some examples from luminosity calibrations of stellar classes. A brief outline is also given of a tentative course of investigations, anticipating future space astrometry missions.

  5. Diagnostic biases in translational bioinformatics.

    PubMed

    Han, Henry

    2015-08-01

    With the surge of translational medicine and computational omics research, complex disease diagnosis is more and more relying on massive omics data-driven molecular signature detection. However, how to detect and prevent possible diagnostic biases in translational bioinformatics remains an unsolved problem despite its importance in the coming era of personalized medicine. In this study, we comprehensively investigate the diagnostic bias problem by analyzing benchmark gene array, protein array, RNA-Seq and miRNA-Seq data under the framework of support vector machines for different model selection methods. We further categorize the diagnostic biases into different types by conducting rigorous kernel matrix analysis and provide effective machine learning methods to conquer the diagnostic biases. In this study, we comprehensively investigate the diagnostic bias problem by analyzing benchmark gene array, protein array, RNA-Seq and miRNA-Seq data under the framework of support vector machines. We have found that the diagnostic biases happen for data with different distributions and SVM with different kernels. Moreover, we identify total three types of diagnostic biases: overfitting bias, label skewness bias, and underfitting bias in SVM diagnostics, and present corresponding reasons through rigorous analysis. Compared with the overfitting and underfitting biases, the label skewness bias is more challenging to detect and conquer because it can be easily confused as a normal diagnostic case from its deceptive accuracy. To tackle this problem, we propose a derivative component analysis based support vector machines to conquer the label skewness bias by achieving the rivaling clinical diagnostic results. Our studies demonstrate that the diagnostic biases are mainly caused by the three major factors, i.e. kernel selection, signal amplification mechanism in high-throughput profiling, and training data label distribution. Moreover, the proposed DCA-SVM diagnosis provides a

  6. Gender bias affects forests worldwide

    Treesearch

    Marlène Elias; Susan S Hummel; Bimbika S Basnett; Carol J.P. Colfer

    2017-01-01

    Gender biases persist in forestry research and practice. These biases result in reduced scientific rigor and inequitable, ineffective, and less efficient policies, programs, and interventions. Drawing from a two-volume collection of current and classic analyses on gender in forests, we outline five persistent and inter-related themes: gendered governance, tree tenure,...

  7. Sequential biases in accumulating evidence

    PubMed Central

    Huggins, Richard; Dogo, Samson Henry

    2015-01-01

    Whilst it is common in clinical trials to use the results of tests at one phase to decide whether to continue to the next phase and to subsequently design the next phase, we show that this can lead to biased results in evidence synthesis. Two new kinds of bias associated with accumulating evidence, termed ‘sequential decision bias’ and ‘sequential design bias’, are identified. Both kinds of bias are the result of making decisions on the usefulness of a new study, or its design, based on the previous studies. Sequential decision bias is determined by the correlation between the value of the current estimated effect and the probability of conducting an additional study. Sequential design bias arises from using the estimated value instead of the clinically relevant value of an effect in sample size calculations. We considered both the fixed‐effect and the random‐effects models of meta‐analysis and demonstrated analytically and by simulations that in both settings the problems due to sequential biases are apparent. According to our simulations, the sequential biases increase with increased heterogeneity. Minimisation of sequential biases arises as a new and important research area necessary for successful evidence‐based approaches to the development of science. © 2015 The Authors. Research Synthesis Methods Published by John Wiley & Sons Ltd. PMID:26626562

  8. Classifying sex biased congenital anomalies

    SciTech Connect

    Lubinsky, M.S.

    1997-03-31

    The reasons for sex biases in congenital anomalies that arise before structural or hormonal dimorphisms are established has long been unclear. A review of such disorders shows that patterning and tissue anomalies are female biased, and structural findings are more common in males. This suggests different gender dependent susceptibilities to developmental disturbances, with female vulnerabilities focused on early blastogenesis/determination, while males are more likely to involve later organogenesis/morphogenesis. A dual origin for some anomalies explains paradoxical reductions of sex biases with greater severity (i.e., multiple rather than single malformations), presumably as more severe events increase the involvement of an otherwise minor process with opposite biases to those of the primary mechanism. The cause for these sex differences is unknown, but early dimorphisms, such as differences in growth or presence of H-Y antigen, may be responsible. This model provides a useful rationale for understanding and classifying sex-biased congenital anomalies. 42 refs., 7 tabs.

  9. Cognitive Bias in Systems Verification

    NASA Technical Reports Server (NTRS)

    Larson, Steve

    2012-01-01

    Working definition of cognitive bias: Patterns by which information is sought and interpreted that can lead to systematic errors in decisions. Cognitive bias is used in diverse fields: Economics, Politics, Intelligence, Marketing, to name a few. Attempts to ground cognitive science in physical characteristics of the cognitive apparatus exceed our knowledge. Studies based on correlations; strict cause and effect is difficult to pinpoint. Effects cited in the paper and discussed here have been replicated many times over, and appear sound. Many biases have been described, but it is still unclear whether they are all distinct. There may only be a handful of fundamental biases, which manifest in various ways. Bias can effect system verification in many ways . Overconfidence -> Questionable decisions to deploy. Availability -> Inability to conceive critical tests. Representativeness -> Overinterpretation of results. Positive Test Strategies -> Confirmation bias. Debiasing at individual level very difficult. The potential effect of bias on the verification process can be managed, but not eliminated. Worth considering at key points in the process.

  10. Bias in occupational epidemiology studies

    PubMed Central

    Pearce, Neil; Checkoway, Harvey; Kriebel, David

    2007-01-01

    The design of occupational epidemiology studies should be based on the need to minimise random and systematic error. The latter is the focus of this paper, and includes selection bias, information bias and confounding. Selection bias can be minimised by obtaining a high response rate (and by appropriate selection of the control group in a case‐control study). In general, it is important to ensure that information bias is minimised and is also non‐differential (for example, that the misclassification of exposure is not related to disease status) by collecting data in a standardised manner. A major concern in occupational epidemiology studies usually relates to confounding, because exposure has not been randomly allocated, and the groups under study may therefore have different baseline disease risks. For each of these types of bias, the goal should be to avoid the bias by appropriate study design and/or appropriate control in the analysis. However, it is also important to attempt to assess the likely direction and strength of biases that cannot be avoided or controlled. PMID:17053019

  11. Hindsight bias around the world.

    PubMed

    Pohl, Rüdiger F; Bender, Michael; Lachmann, Gregor

    2002-01-01

    Hindsight bias refers to the tendency to overestimate in hindsight what one has known in foresight. Recently, two experiments extended the research to include samples from different cultures (Choi & Nisbett, 2000; Heine & Lehman, 1996). Asking their participants what they would have guessed before they knew the outcome ("hypothetical design"), Choi and Nisbett (2000) found that Koreans, in comparison to North Americans, exhibited more hindsight bias. Heine and Lehman (1996), however, reported that Japanese people in comparison to Canadians showed marginally less hindsight bias. In a second study, in which participants were asked to recall what they had estimated before they knew the outcome ("memory design"), the latter authors found no difference in hindsight bias between Japanese people and Canadians. We extended these studies with 225 Internet participants, in a hypothetical design, from four different continents (Asia, Australia, Europe, and North America). Hindsight bias was large and similar for all samples except for German and Dutch participants who showed no hindsight bias at all. While the latter effect may be based on peculiarities of the material and of the participants, the former underscores the worldwide stability of the phenomenon. In addition a follow-up surprise rating (paper and pencil) in China (35 participants) and Germany (20 participants) revealed that only less surprising items led to hindsight bias while more surprising ones did not. We suggest that the basic cognitive processes leading to hindsight bias are by-products of the evolutionary-evolved capacity of adaptive learning. On top of these basic processes, individual meta-cognitions (e.g., elicited by surprise) or motives (e.g., a self-serving motive) may further moderate the amount of bias, thus explaining the diverging results of Choi and Nisbett (2000), Heine and Lehman (1996), and our own study.

  12. Automated Confocal Microscope Bias Correction

    NASA Astrophysics Data System (ADS)

    Dorval, Thierry; Genovesio, Auguste

    2006-10-01

    Illumination artifacts systematically occur in 2D cross-section confocal microscopy imaging . These bias can strongly corrupt an higher level image processing such as a segmentation, a fluorescence evaluation or even a pattern extraction/recognition. This paper presents a new fully automated bias correction methodology based on large image database preprocessing. This method is very appropriate to the High Content Screening (HCS), method dedicated to drugs discovery. Our method assumes that the amount of pictures available is large enough to allow a reliable statistical computation of an average bias image. A relevant segmentation evaluation protocol and experimental results validate our correction algorithm by outperforming object extraction on non corrupted images.

  13. Linear and non-linear bias: predictions versus measurements

    NASA Astrophysics Data System (ADS)

    Hoffmann, K.; Bel, J.; Gaztañaga, E.

    2017-02-01

    We study the linear and non-linear bias parameters which determine the mapping between the distributions of galaxies and the full matter density fields, comparing different measurements and predictions. Associating galaxies with dark matter haloes in the Marenostrum Institut de Ciències de l'Espai (MICE) Grand Challenge N-body simulation, we directly measure the bias parameters by comparing the smoothed density fluctuations of haloes and matter in the same region at different positions as a function of smoothing scale. Alternatively, we measure the bias parameters by matching the probability distributions of halo and matter density fluctuations, which can be applied to observations. These direct bias measurements are compared to corresponding measurements from two-point and different third-order correlations, as well as predictions from the peak-background model, which we presented in previous papers using the same data. We find an overall variation of the linear bias measurements and predictions of ˜5 per cent with respect to results from two-point correlations for different halo samples with masses between ˜1012and1015 h-1 M⊙ at the redshifts z = 0.0 and 0.5. Variations between the second- and third-order bias parameters from the different methods show larger variations, but with consistent trends in mass and redshift. The various bias measurements reveal a tight relation between the linear and the quadratic bias parameters, which is consistent with results from the literature based on simulations with different cosmologies. Such a universal relation might improve constraints on cosmological models, derived from second-order clustering statistics at small scales or higher order clustering statistics.

  14. Parenting practices, interpretive biases, and anxiety in Latino children.

    PubMed

    Varela, R Enrique; Niditch, Laura A; Hensley-Maloney, Lauren; Moore, Kathryn W; Creveling, C Christiane

    2013-03-01

    A number of factors are believed to confer risk for anxiety development in children; however, cultural variation of purported risk factors remains unclear. We examined relations between controlling and rejecting parenting styles, parental modeling of anxious behaviors, child interpretive biases, and child anxiety in a mixed clinically anxious (n=27) and non-clinical (n=20) sample of Latino children and at least one of their parents. Families completed discussion-based tasks and questionnaires in a lab setting. Results indicated that child anxiety was: linked with parental control and child interpretative biases, associated with parental modeling of anxious behaviors at a trend level, and not associated with low parental acceptance. Findings that controlling parenting and child interpretive biases were associated with anxiety extend current theories of anxiety development to the Latino population. We speculate that strong family ties may buffer Latino children from detrimental effects of perceived low parental acceptance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Parenting Practices, Interpretive Biases, and Anxiety in Latino Children

    PubMed Central

    Varela, R. Enrique; Niditch, Laura A.; Hensley-Maloney, Lauren; Moore, Kathryn W.; Creveling, C. Christiane

    2013-01-01

    A number of factors are believed to confer risk for anxiety development in children; however, cultural variation of purported risk factors remains unclear. We examined relations between controlling and rejecting parenting styles, parental modeling of anxious behaviors, child interpretive biases, and child anxiety in a mixed clinically anxious (n = 27) and non-clinical (n = 20) sample of Latino children and at least one of their parents. Families completed discussion-based tasks and questionnaires in a lab setting. Results indicated that child anxiety was: linked with parental control and child interpretative biases; associated with parental modeling of anxious behaviors at a trend level; and not associated with low parental acceptance. Findings that controlling parenting and child interpretive biases were associated with anxiety extend current theories of anxiety development to the Latino population. We speculate that strong family ties may buffer Latino children from detrimental effects of perceived low parental acceptance. PMID:23434545

  16. Magnetic bearings with zero bias

    NASA Technical Reports Server (NTRS)

    Brown, Gerald V.; Grodsinsky, Carlos M.

    1991-01-01

    A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

  17. Perspectives of voltage control for magnetic exchange bias in multiferroic heterostructures

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Zhou, Z.; Sun, N. X.; Liu, M.

    2017-04-01

    Exchange bias, as an internal magnetic bias induced by a ferromagnetic-antiferromagnetic exchange coupling, is extremely important in many magnetic applications such as memories, sensors and other devices. Voltage control of exchange bias in multiferroics provides an energy-efficient way to achieve a rapidly 180° deterministic switching of magnetization, which has been considered as a key challenge in realizing next generation of fast, compact and ultra-low power magnetoelectric memories and sensors. Additionally, exchange bias can enhance dynamic magnetoelectric coupling strength in an external-field-free manner. In this paper, we provide a perspective on voltage control of exchange bias in different multiferroic heterostructures. Brief mechanization and related experiments are discussed as well as future trend and challenges that can be overcome by electrically tuning of exchange bias in state-of-the-art magnetoelectric devices.

  18. Expectancy bias in anxious samples

    PubMed Central

    Cabeleira, Cindy M.; Steinman, Shari A.; Burgess, Melissa M.; Bucks, Romola S.; MacLeod, Colin; Melo, Wilson; Teachman, Bethany A.

    2014-01-01

    While it is well documented that anxious individuals have negative expectations about the future, it is unclear what cognitive processes give rise to this expectancy bias. Two studies are reported that use the Expectancy Task, which is designed to assess expectancy bias and illuminate its basis. This task presents individuals with valenced scenarios (Positive Valence, Negative Valence, or Conflicting Valence), and then evaluates their tendency to expect subsequent future positive relative to negative events. The Expectancy Task was used with low and high trait anxious (Study 1: N = 32) and anxiety sensitive (Study 2: N = 138) individuals. Results suggest that in the context of physical concerns, both high anxious samples display a less positive expectancy bias. In the context of social concerns, high trait anxious individuals display a negative expectancy bias only when negatively valenced information was previously presented. Overall, this suggests that anxious individuals display a less positive expectancy bias, and that the processes that give rise to this bias may vary by type of situation (e.g., social or physical) or anxiety difficulty. PMID:24798678

  19. Trends in Southern Ocean Eddy Kinetic Energy

    NASA Astrophysics Data System (ADS)

    Chambers, Don

    2016-04-01

    A recent study by Hogg et al. (JGR, 2015) has demonstrated a 20-year trend in eddy kinetic energy (EKE) computed from satellite altimetry data. However, this estimate is based on an averaging over large spatial areas. In this study, we use the same methods to examine regional EKE trends throughout the Southern Ocean, from 1993-2015. We do find significant positive trends in several areas of the Southern Ocean, mainly in regions with high mean EKE associated with interactions between jets and bathymetry. At the same time, however, there are also regions with significant negative trends. Overall, EKE in the majority of the Southern Ocean has not changed. These results suggest that the estimates of Hogg et al. may have been biased by these regional extremes, and that more work is needed to quantify climatic changes in EKE.

  20. Negativity Bias in Dangerous Drivers

    PubMed Central

    Chai, Jing; Qu, Weina; Sun, Xianghong; Zhang, Kan; Ge, Yan

    2016-01-01

    The behavioral and cognitive characteristics of dangerous drivers differ significantly from those of safe drivers. However, differences in emotional information processing have seldom been investigated. Previous studies have revealed that drivers with higher anger/anxiety trait scores are more likely to be involved in crashes and that individuals with higher anger traits exhibit stronger negativity biases when processing emotions compared with control groups. However, researchers have not explored the relationship between emotional information processing and driving behavior. In this study, we examined the emotional information processing differences between dangerous drivers and safe drivers. Thirty-eight non-professional drivers were divided into two groups according to the penalty points that they had accrued for traffic violations: 15 drivers with 6 or more points were included in the dangerous driver group, and 23 drivers with 3 or fewer points were included in the safe driver group. The emotional Stroop task was used to measure negativity biases, and both behavioral and electroencephalograph data were recorded. The behavioral results revealed stronger negativity biases in the dangerous drivers than in the safe drivers. The bias score was correlated with self-reported dangerous driving behavior. Drivers with strong negativity biases reported having been involved in mores crashes compared with the less-biased drivers. The event-related potentials (ERPs) revealed that the dangerous drivers exhibited reduced P3 components when responding to negative stimuli, suggesting decreased inhibitory control of information that is task-irrelevant but emotionally salient. The influence of negativity bias provides one possible explanation of the effects of individual differences on dangerous driving behavior and traffic crashes. PMID:26765225

  1. Socially biased learning in monkeys.

    PubMed

    Fragaszy, D; Visalberghi, E

    2004-02-01

    We review socially biased learning about food and problem solving in monkeys, relying especially on studies with tufted capuchin monkeys (Cebus apella) and callitrichid monkeys. Capuchin monkeys most effectively learn to solve a new problem when they can act jointly with an experienced partner in a socially tolerant setting and when the problem can be solved by direct action on an object or substrate, but they do not learn by imitation. Capuchin monkeys are motivated to eat foods, whether familiar or novel, when they are with others that are eating, regardless of what the others are eating. Thus, social bias in learning about foods is indirect and mediated by facilitation of feeding. In most respects, social biases in learning are similar in capuchins and callitrichids, except that callitrichids provide more specific behavioral cues to others about the availability and palatability of foods. Callitrichids generally are more tolerant toward group members and coordinate their activity in space and time more closely than capuchins do. These characteristics support stronger social biases in learning in callitrichids than in capuchins in some situations. On the other hand, callitrichids' more limited range of manipulative behaviors, greater neophobia, and greater sensitivity to the risk of predation restricts what these monkeys learn in comparison with capuchins. We suggest that socially biased learning is always the collective outcome of interacting physical, social, and individual factors, and that differences across populations and species in social bias in learning reflect variations in all these dimensions. Progress in understanding socially biased learning in nonhuman species will be aided by the development of appropriately detailed models of the richly interconnected processes affecting learning.

  2. Assessing attentional biases with stuttering.

    PubMed

    Lowe, Robyn; Menzies, Ross; Packman, Ann; O'Brian, Sue; Jones, Mark; Onslow, Mark

    2016-01-01

    Many adults who stutter presenting for speech treatment experience social anxiety disorder. The presence of mental health disorders in adults who stutter has been implicated in a failure to maintain speech treatment benefits. Contemporary theories of social anxiety disorder propose that the condition is maintained by negative cognitions and information processing biases. Consistent with cognitive theories, the probe detection task has shown that social anxiety is associated with an attentional bias to avoid social information. This information processing bias is suggested to be involved in maintaining anxiety. Evidence is emerging for information processing biases being involved with stuttering. This study investigated information processing in adults who stutter using the probe detection task. Information processing biases have been implicated in anxiety maintenance in social anxiety disorder and therefore may have implications for the assessment and treatment of stuttering. It was hypothesized that stuttering participants compared with control participants would display an attentional bias to avoid attending to social information. Twenty-three adults who stutter and 23 controls completed a probe detection task in which they were presented with pairs of photographs: a face displaying an emotional expression-positive, negative or neutral-and an everyday household object. All participants were subjected to a mild social threat induction being told they would speak to a small group of people on completion of the task. The stuttering group scored significantly higher than controls for trait anxiety, but did not differ from controls on measures of social anxiety. Non-socially anxious adults who stutter did not display an attentional bias to avoid looking at photographs of faces relative to everyday objects. Higher scores on trait anxiety were positively correlated with attention towards photographs of negative faces. Attentional biases as assessed by the probe

  3. Exchange biasing of magnetoelectric composites.

    PubMed

    Lage, Enno; Kirchhof, Christine; Hrkac, Viktor; Kienle, Lorenz; Jahns, Robert; Knöchel, Reinhard; Quandt, Eckhard; Meyners, Dirk

    2012-04-22

    Magnetoelectric composite materials are promising candidates for highly sensitive magnetic-field sensors. However, the composites showing the highest reported magnetoelectric coefficients require the presence of external d.c. magnetic bias fields, which is detrimental to their use as sensitive high-resolution magnetic-field sensors. Here, we report magnetoelectric composite materials that instead rely on intrinsic magnetic fields arising from exchange bias in the device. Thin-film magnetoelectric two-two composites were fabricated by magnetron sputtering on silicon-cantilever substrates. The composites consist of piezoelectric AlN and multilayers with the sequence Ta/Cu/Mn(70)Ir(30)/Fe(50)Co(50) or Ta/Cu/Mn(70)Ir(30)/Fe(70.2)Co(7.8)Si(12)B(10) serving as the magnetostrictive component. The thickness of the ferromagnetic layers and angle dependency of the exchange bias field are used to adjust the shift of the magnetostriction curve in such a way that the maximum piezomagnetic coefficient occurs at zero magnetic bias field. These self-biased composites show high sensitivity to a.c. magnetic fields with a maximum magnetoelectric coefficient of 96 V cm(-1) Oe(-1) at mechanical resonance.

  4. Exchange biasing of magnetoelectric composites

    NASA Astrophysics Data System (ADS)

    Lage, Enno; Kirchhof, Christine; Hrkac, Viktor; Kienle, Lorenz; Jahns, Robert; Knöchel, Reinhard; Quandt, Eckhard; Meyners, Dirk

    2012-06-01

    Magnetoelectric composite materials are promising candidates for highly sensitive magnetic-field sensors. However, the composites showing the highest reported magnetoelectric coefficients require the presence of external d.c. magnetic bias fields, which is detrimental to their use as sensitive high-resolution magnetic-field sensors. Here, we report magnetoelectric composite materials that instead rely on intrinsic magnetic fields arising from exchange bias in the device. Thin-film magnetoelectric two-two composites were fabricated by magnetron sputtering on silicon-cantilever substrates. The composites consist of piezoelectric AlN and multilayers with the sequence Ta/Cu/Mn70Ir30/Fe50Co50 or Ta/Cu/Mn70Ir30/Fe70.2Co7.8Si12B10 serving as the magnetostrictive component. The thickness of the ferromagnetic layers and angle dependency of the exchange bias field are used to adjust the shift of the magnetostriction curve in such a way that the maximum piezomagnetic coefficient occurs at zero magnetic bias field. These self-biased composites show high sensitivity to a.c. magnetic fields with a maximum magnetoelectric coefficient of 96 V cm-1 Oe-1 at mechanical resonance.

  5. Diamond nucleation under bias conditions

    SciTech Connect

    Stoeckel, R.; Stammler, M.; Janischowsky, K.; Ley, L.; Albrecht, M.; Strunk, H.P.

    1998-01-01

    The so-called bias pretreatment allows the growth of heteroepitaxial diamond films by plasma chemical vapor deposition on silicon (100) surfaces. We present plan-view and cross-sectional transmission electron micrographs of the substrate surface at different phases of the bias pretreatment. These observations are augmented by measurements of the etch rates of Si, SiC, and different carbon modifications under plasma conditions and the size distribution of oriented diamond crystals grown after bias pretreatment. Based on these results a new model for diamond nucleation under bias conditions is proposed. First, a closed layer of nearly epitaxially oriented cubic SiC with a thickness of about 10 nm is formed. Subplantation of carbon into this SiC layer causes a supersaturation with carbon and results in the subcutaneous formation of epitaxially oriented nucleation centers in the SiC layer. Etching of the SiC during the bias pretreatment as well as during diamond growth brings these nucleation centers to the sample surface and causes the growth of diamonds epitaxially oriented on the Si/SiC substrate. {copyright} {ital 1998 American Institute of Physics.}

  6. Heuristic-biased stochastic sampling

    SciTech Connect

    Bresina, J.L.

    1996-12-31

    This paper presents a search technique for scheduling problems, called Heuristic-Biased Stochastic Sampling (HBSS). The underlying assumption behind the HBSS approach is that strictly adhering to a search heuristic often does not yield the best solution and, therefore, exploration off the heuristic path can prove fruitful. Within the HBSS approach, the balance between heuristic adherence and exploration can be controlled according to the confidence one has in the heuristic. By varying this balance, encoded as a bias function, the HBSS approach encompasses a family of search algorithms of which greedy search and completely random search are extreme members. We present empirical results from an application of HBSS to the realworld problem of observation scheduling. These results show that with the proper bias function, it can be easy to outperform greedy search.

  7. Exchange-biased magnetic vortices.

    SciTech Connect

    Hoffmann, A.; Sort, J.; Buchanan, K. S.; Nogues, J.; Inst. Catalana de Recerca i Estudis Avancats; Univ. Autonoma de Barcelona

    2008-07-01

    This paper reviews our work on the interplay between exchange bias due to the coupling of a ferromagnet to an antiferromagnet and the formation of magnetic vortices, which occur due to the patterning of a ferromagnet. Depending on the thermal and magnetic history, a variety of different effects can be observed. Thermal annealing in a saturating magnetic field establishes a spatially homogeneous exchange bias with a uniform unidirectional anisotropy. This results in an angular dependence of the magnetization reversal mode, which can be either via magnetization rotation or vortex nucleation and annihilation. In contrast, thermal annealing in a field smaller than the vortex annihilation field imprints the ferromagnetic vortex configuration in the antiferromagnet with high fidelity resulting in unusual asymmetric hysteresis loops. Furthermore, we discuss how the interfacial nature of the exchange bias can modify the vortex magnetization along the thickness of the ferromagnet.

  8. Anchoring bias in online voting

    NASA Astrophysics Data System (ADS)

    Yang, Zimo; Zhang, Zi-Ke; Zhou, Tao

    2012-12-01

    Voting online with explicit ratings could largely reflect people's preferences and objects' qualities, but ratings are always irrational, because they may be affected by many unpredictable factors like mood, weather and other people's votes. By analyzing two real systems, this paper reveals a systematic bias embedding in the individual decision-making processes, namely people tend to give a low rating after a low rating, as well as a high rating following a high rating. This so-called anchoring bias is validated via extensive comparisons with null models, and numerically speaking, the extent of bias decays with voting interval in a logarithmic form. Our findings could be applied in the design of recommender systems and considered as important complementary materials to previous knowledge about anchoring effects on financial trades, performance judgments, auctions, and so on.

  9. Unpacking the Evidence of Gender Bias

    ERIC Educational Resources Information Center

    Fulmer, Connie L.

    2010-01-01

    The purpose of this study was to investigate gender bias in pre-service principals using the Gender-Leader Implicit Association Test. Analyses of student-learning narratives revealed how students made sense of gender bias (biased or not-biased) and how each reacted to evidence (surprised or not-surprised). Two implications were: (1) the need for…

  10. Collection Development and the Psychology of Bias

    ERIC Educational Resources Information Center

    Quinn, Brian

    2012-01-01

    The library literature addressing the role of bias in collection development emphasizes a philosophical approach. It is based on the notion that bias can be controlled by the conscious act of believing in certain values and adhering to a code of ethics. It largely ignores the psychological research on bias, which suggests that bias is a more…

  11. Optimistic bias, sexual assault, and fear.

    PubMed

    Chapin, John R; Pierce, Mari

    2012-01-01

    A survey of 431 adults documents optimistic bias regarding people's perceived risk of sexual victimization. The findings extend optimistic bias to crime victimization and contribute to the literature by considering a motivational factor, fear, as a predictor of optimistic bias. The study also yielded significant relationships between optimistic bias and demographic variables, including age, gender, and family structure.

  12. Collection Development and the Psychology of Bias

    ERIC Educational Resources Information Center

    Quinn, Brian

    2012-01-01

    The library literature addressing the role of bias in collection development emphasizes a philosophical approach. It is based on the notion that bias can be controlled by the conscious act of believing in certain values and adhering to a code of ethics. It largely ignores the psychological research on bias, which suggests that bias is a more…

  13. Without Bias: A Guidebook for Nondiscriminatory Communication.

    ERIC Educational Resources Information Center

    Pickens, Judy E., Ed.; And Others

    This guidebook discusses ways to eliminate various types of discrimination from business communications. Separately authored chapters discuss eliminating racial and ethnic bias; eliminating sexual bias; achieving communication sensitive about handicaps of disabled persons; eliminating bias from visual media; eliminating bias from meetings,…

  14. Unpacking the Evidence of Gender Bias

    ERIC Educational Resources Information Center

    Fulmer, Connie L.

    2010-01-01

    The purpose of this study was to investigate gender bias in pre-service principals using the Gender-Leader Implicit Association Test. Analyses of student-learning narratives revealed how students made sense of gender bias (biased or not-biased) and how each reacted to evidence (surprised or not-surprised). Two implications were: (1) the need for…

  15. The Truth and Bias Model of Judgment

    ERIC Educational Resources Information Center

    West, Tessa V.; Kenny, David A.

    2011-01-01

    We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of…

  16. Measurement Bias Detection through Factor Analysis

    ERIC Educational Resources Information Center

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

  17. Measurement Bias Detection through Factor Analysis

    ERIC Educational Resources Information Center

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

  18. The Truth and Bias Model of Judgment

    ERIC Educational Resources Information Center

    West, Tessa V.; Kenny, David A.

    2011-01-01

    We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of…

  19. The Threshold of Embedded M Collider Bias and Confounding Bias

    ERIC Educational Resources Information Center

    Kelcey, Benjamin; Carlisle, Joanne

    2011-01-01

    Of particular import to this study, is collider bias originating from stratification on retreatment variables forming an embedded M or bowtie structural design. That is, rather than assume an M structural design which suggests that "X" is a collider but not a confounder, the authors adopt what they consider to be a more reasonable…

  20. Solar array/spacecraft biasing

    NASA Technical Reports Server (NTRS)

    Fitzgerald, D. J.

    1981-01-01

    Biasing techniques and their application to the control of spacecraft potential is discussed. Normally when a spacecraft is operated with ion thrusters, the spacecraft will be 10-20 volts negative of the surrounding plasma. This will affect scientific measurements and will allow ions from the charge-exchange plasma to bombard the spacecraft surfaces with a few tens of volts of energy. This condition may not be tolerable. A proper bias system is described that can bring the spacecraft to or near the potential of the surrounding plasma.

  1. Solar array/spacecraft biasing

    NASA Technical Reports Server (NTRS)

    Fitzgerald, D. J.

    1981-01-01

    Biasing techniques and their application to the control of spacecraft potential is discussed. Normally when a spacecraft is operated with ion thrusters, the spacecraft will be 10-20 volts negative of the surrounding plasma. This will affect scientific measurements and will allow ions from the charge-exchange plasma to bombard the spacecraft surfaces with a few tens of volts of energy. This condition may not be tolerable. A proper bias system is described that can bring the spacecraft to or near the potential of the surrounding plasma.

  2. The Electrically Controlled Exchange Bias

    NASA Astrophysics Data System (ADS)

    Harper, Jacob

    Controlling magnetism via voltage in the virtual absence of electric current is the key to reduce power consumption while enhancing processing speed, integration density and functionality in comparison with present-day information technology. Almost all spintronic devices rely on tailored interface magnetism. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is therefore a key challenge to better spintronics. However, there is no direct interaction between magnetization and electric fields, thus making voltage control of magnetism in general a scientific challenge. The significance of controlled interface magnetism started with the exchange-bias effect. Exchange bias is a coupling phenomenon at magnetic interfaces that manifests itself prominently in the shift of the ferromagnetic hysteresis loop along the magnetic-field axis. Various attempts on controlling exchange bias via voltage utilizing different scientific principles have been intensively studied recently. The majority of present research is emphasizing on various complex oxides. Our approach can be considered as a paradigm shift away from complex oxides. We focus on a magnetoelectric antiferromagnetic simple oxide Cr2O3. From a combination of experimental and theoretical efforts, we show that the (0001) surface of magnetoelectric Cr2O3 has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr2O3 single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This is a significant scientific breakthrough providing a new route towards potentially revolutionizing information technology. In addition, a second path of electrically controlled exchange bias is introduced by exploiting the piezoelectric property of BaTiO3. An exchange-bias Co

  3. Bias correction with Data Assimilation

    NASA Astrophysics Data System (ADS)

    Canter, Martin; Barth, Alexander

    2015-04-01

    With this work, we aim at developping a new method of bias correction using data assimilation. This method is based on the stochastic forcing of a model to correct bias. First, through a preliminary run, we estimate the bias of the model and its possible sources. Then, we establish a forcing term which is directly added inside the model's equations. We create an ensemble of runs and consider the forcing term as a control variable during the assimilation of observations. We then use this analysed forcing term to correct the bias of the model. Since the forcing is added inside the model, it acts as a source term, unlike external forcings such as wind. This procedure has been developed and successfully tested with a twin experiment on a Lorenz 95 model. Indeed, we were able to estimate and recover an artificial bias that had been added into the model. This bias had a spatial structure and was constant through time. The mean and behaviour of the corrected model corresponded to those the reference model. It is currently being applied and tested on the sea ice ocean NEMO LIM model, which is used in the PredAntar project. NEMO LIM is a global and low resolution (2 degrees) coupled model (hydrodynamic model and sea ice model) with long time steps allowing simulations over several decades. Due to its low resolution, the model is subject to bias in area where strong currents are present. We aim at correcting this bias by using perturbed current fields from higher resolution models and randomly generated perturbations. The random perturbations need to be constrained in order to respect the physical properties of the ocean, and not create unwanted phenomena. To construct those random perturbations, we first create a random field with the Diva tool (Data-Interpolating Variational Analysis). Using a cost function, this tool penalizes abrupt variations in the field, while using a custom correlation length. It also decouples disconnected areas based on topography. Then, we filter

  4. Drivers, Trends and Mitigation

    SciTech Connect

    Blanco, Arthur S.; Gerlagh, Reyer; Suh, Sangwon; Barrett, John A.; de Coninck, Heleen; Diaz Morejon, Cristobal Felix; Mathur, Ritu; Nakicenovic, Nebojsa; Ahenkorah, Alfred Ofosu; Pan, Jiahua; Pathak, Himanshu; Rice, Jake; Richels, Richard G.; Smith, Steven J.; Stern, David; Toth, Ferenc L.; Zhou, Peter

    2014-12-01

    Chapter 5 analyzes the anthropogenic greenhouse gas (GHG) emission trends until the present and the main drivers that explain those trends. The chapter uses different perspectives to analyze past GHG-emissions trends, including aggregate emissions flows and per capita emissions, cumulative emissions, sectoral emissions, and territory-based vs. consumption-based emissions. In all cases, global and regional trends are analyzed. Where appropriate, the emission trends are contextualized with long-term historic developments in GHG emissions extending back to 1750.

  5. Bias in Dynamic Monte Carlo Alpha Calculations

    SciTech Connect

    Sweezy, Jeremy Ed; Nolen, Steven Douglas; Adams, Terry R.; Trahan, Travis John

    2015-02-06

    A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.

  6. Combating Anti-Muslim Bias

    ERIC Educational Resources Information Center

    Shah, Nirvi

    2011-01-01

    America's 2.5 million Muslims make up less than 1% of the U.S. population, according to the Pew Research Center. Many Muslim students face discrimination and some cases have warranted investigation by the U.S. Department of Education's Office of Civil Rights. Muslim groups have reported widespread bias as well. For many Muslim…

  7. Response Bias in Hospice Evaluation.

    ERIC Educational Resources Information Center

    Hayslip, Bert, Jr.; And Others

    1991-01-01

    Analyzed response bias among 34 recipients of care in hospice. Found nonrespondents to have better bereavement prognoses and tended to care for patients who were younger, male, and in program for shorter time. Nonrespondents were in contact with staff less than were respondents. Data are consistent with earlier research showing significant…

  8. Attributional Bias and Course Evaluations.

    ERIC Educational Resources Information Center

    Gigliotti, Richard J.; Buchtel, Foster S.

    1990-01-01

    How self-serving bias affects evaluations of college courses was tested for 691 students by comparing a model predicting that evaluations reflect actual grades with a model predicting that evaluations reflect confirmation or disconfirmation of expectations. Results support course evaluation validity by indicating a minimal effect of self-serving…

  9. Test Bias and Construct Validity.

    ERIC Educational Resources Information Center

    Jensen, Arthur R.

    The several statistical methods described for detecting test bias in terms of various internal features of a person's test performances and the test's construct validity can be applied to any groups in the population. But the evidence regarding groups other than U.S. blacks and whites is either lacking or is still too sketchy to permit any strong…

  10. Key Words in Instruction. Bias

    ERIC Educational Resources Information Center

    Callison, Daniel

    2005-01-01

    Two challenging criteria for judging information involve bias and authority. In both cases, judgments may not be clearly possible. In both cases, there may be degrees or levels of acceptability. For students to gain experience and to demonstrate skills in making judgments, they need opportunities to consider a wide spectrum of resources under a…

  11. Cultural Bias in Testing ESL.

    ERIC Educational Resources Information Center

    Cargill-Power, C.

    Although cultural content is unavoidable as a backdrop for good language testing, cultural bias in testing English as a second language presents many dangers. A picture cue calling for a correct grammatical response may evoke an incorrect answer if the pictorial content is culturally coded. The cultural background behind a test must be accurately…

  12. The Identification of Biased Items.

    ERIC Educational Resources Information Center

    Sinnott, Loraine T.

    A standard method for exploring item bias is the intergroup comparison of item difficulties. This paper describes a refinement and generalization of this technique. In contrast to prior approaches, the proposed method deletes outlying items from the formulation of a criterion for identifying items as deviant. It also extends the mathematical…

  13. Recall bias, MMR, and autism.

    PubMed

    Andrews, N; Miller, E; Taylor, B; Lingam, R; Simmons, A; Stowe, J; Waight, P

    2002-12-01

    Parents of autistic children with regressive symptoms who were diagnosed after the publicity alleging a link with measles, mumps, and rubella (MMR) vaccine tended to recall the onset as shortly after MMR more often than parents of similar children who were diagnosed prior to the publicity. This is consistent with the recall bias expected under such circumstances.

  14. Gender Bias in the Courts.

    ERIC Educational Resources Information Center

    Gill, Wanda E.

    The term gender bias was coined by the National Judicial Education Program to Promote Equality for Women and Men in the Courts and is defined as the predisposition or tendency to think about and behave toward people primarily on the basis of their sex rather than their status, professional accomplishments, or aspirations. An effective method for…

  15. Stereotype Formation: Biased by Association

    ERIC Educational Resources Information Center

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

  16. Attentional bias in math anxiety

    PubMed Central

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms. PMID:26528208

  17. Misclassification bias in areal estimates

    Treesearch

    Raymond L. Czaplewski

    1992-01-01

    In addition to thematic maps, remote sensing provides estimates of area in different thematic categories. Areal estimates are frequently used for resource inventories, management planning, and assessment analyses. Misclassification causes bias in these statistical areal estimates. For example, if a small percentage of a common cover type is misclassified as a rare...

  18. Sex Bias in Counseling Materials

    ERIC Educational Resources Information Center

    Harway, Michele

    1977-01-01

    This article reviews findings of bias in counseling materials and presents results of three original studies. Indications are that textbooks used by practitioners present the sexes in stereotypical fashion, and a greater proportion of college catalog context is devoted to men than to women. (Author)

  19. Combating Anti-Muslim Bias

    ERIC Educational Resources Information Center

    Shah, Nirvi

    2011-01-01

    America's 2.5 million Muslims make up less than 1% of the U.S. population, according to the Pew Research Center. Many Muslim students face discrimination and some cases have warranted investigation by the U.S. Department of Education's Office of Civil Rights. Muslim groups have reported widespread bias as well. For many Muslim…

  20. Are Culturally Biased Test Useful?

    ERIC Educational Resources Information Center

    Kelley, H. Paul

    1982-01-01

    Whether culturally biased tests are useful depends on what is meant by that phrase and the purpose for which the test is to be used. Keeping the distinction between aptitude and achievement in mind, different definitions of fair use of tests come from different sets of societal values. (Author/CM)

  1. Stereotype Formation: Biased by Association

    ERIC Educational Resources Information Center

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

  2. Physician Racial Bias and Word Use during Racially Discordant Medical Interactions.

    PubMed

    Hagiwara, Nao; Slatcher, Richard B; Eggly, Susan; Penner, Louis A

    2017-04-01

    Physician racial bias can negatively affect Black patients' reactions to racially discordant medical interactions, suggesting that racial bias is manifested in physicians' communication with their Black patients. However, little is known about how physician racial bias actually influences their communication during these interactions. This study investigated how non-Black physicians' racial bias is related to their word use during medical interactions with Black patients. One hundred and seventeen video-recorded racially discordant medical interactions from a larger study were transcribed and analyzed using Linguistic Inquiry and Word Count (LIWC) software. Physicians with higher levels of implicit racial bias used first-person plural pronouns and anxiety-related words more frequently than physicians with lower levels of implicit bias. There was also a trend for physicians with higher levels of explicit racial bias to use first-person singular pronouns more frequently than physicians with lower levels of explicit bias. These findings suggest that non-Black physicians with higher levels of implicit racial bias may tend to use more words that reflect social dominance (i.e., first-person plural pronouns) and anxiety when interacting with Black patients.

  3. Intragenic Spatial Patterns of Codon Usage Bias in Prokaryotic and Eukaryotic Genomes

    PubMed Central

    Qin, Hong; Wu, Wei Biao; Comeron, Josep M.; Kreitman, Martin; Li, Wen-Hsiung

    2004-01-01

    To study the roles of translational accuracy, translational efficiency, and the Hill-Robertson effect in codon usage bias, we studied the intragenic spatial distribution of synonymous codon usage bias in four prokaryotic (Escherichia coli, Bacillus subtilis, Sulfolobus tokodaii, and Thermotoga maritima) and two eukaryotic (Saccharomyces cerevisiae and Drosophila melanogaster) genomes. We generated supersequences at each codon position across genes in a genome and computed the overall bias at each codon position. By quantitatively evaluating the trend of spatial patterns using isotonic regression, we show that in yeast and prokaryotic genomes, codon usage bias increases along translational direction, which is consistent with purifying selection against nonsense errors. Fruit fly genes show a nearly symmetric M-shaped spatial pattern of codon usage bias, with less bias in the middle and both ends. The low codon usage bias in the middle region is best explained by interference (the Hill-Robertson effect) between selections at different codon positions. In both yeast and fruit fly, spatial patterns of codon usage bias are characteristically different from patterns of GC-content variations. Effect of expression level on the strength of codon usage bias is more conspicuous than its effect on the shape of the spatial distribution. PMID:15611189

  4. Anticlockwise or Clockwise? A Dynamic Perception-Action-Laterality Model for Directionality Bias in Visuospatial Functioning

    PubMed Central

    Karim, A.K.M. Rezaul; Proulx, Michael J.; Likova, Lora T.

    2016-01-01

    Reviewing the relevant literature in visual psychophysics and visual neuroscience we propose a three-stage model of directionality bias in visuospatial functioning. We call this model the ‘Perception-Action-Laterality’ (PAL) hypothesis. We analyzed the research findings for a wide range of visuospatial tasks, showing that there are two major directionality trends: clockwise versus anticlockwise. It appears these preferences are combinatorial, such that a majority of people fall in the first category demonstrating a preference for stimuli/objects arranged from left-to-right rather than from right-to-left, while people in the second category show an opposite trend. These perceptual biases can guide sensorimotor integration and action, creating two corresponding turner groups in the population. In support of PAL, we propose another model explaining the origins of the biases– how the neurogenetic factors and the cultural factors interact in a biased competition framework to determine the direction and extent of biases. This dynamic model can explain not only the two major categories of biases, but also the unbiased, unreliably biased or mildly biased cases in visuosptial functioning. PMID:27350096

  5. Is the global mean temperature trend too low?

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2015-04-01

    The global mean temperature trend may be biased due to similar technological and economic developments worldwide. In this study we want to present a number of recent results that suggest that the global mean temperature trend might be steeper as generally thought. In the Global Historical Climate Network version 3 (GHCNv3) the global land surface temperature is estimated to have increased by about 0.8°C between 1880 and 2012. In the raw temperature record, the increase is 0.6°C; the 0.2°C difference is due to homogenization adjustments. Given that homogenization can only reduce biases, this 0.2°C stems from a partial correction of bias errors and it seems likely that the real non-climatic trend bias will be larger. Especially in regions with sparser networks, homogenization will not be able to improve the trend much. Thus if the trend bias in these regions is similar to the bias for more dense networks (industrialized countries), one would expect the real bias to be larger. Stations in sparse networks are representative for a larger region and are given more weight in the computation of the global mean temperature. If all stations are given equal weight, the homogenization adjustments of the GHCNv3 dataset are about 0.4°C per century. In the subdaily HadISH dataset one break with mean size 0.12°C is found every 15 years for the period 1973-2013. That would be a trend bias of 0.78°C per century on a station by station basis. Unfortunately, these estimates strongly focus on Western countries having more stations. It is known from the literature that rich countries have a (statistically insignificant) stronger trend in the global datasets. Regional datasets can be better homogenized than global ones, the main reason being that global datasets do not contain all stations known to the weather services. Furthermore, global datasets use automatic homogenization methods and have less or no metadata. Thus while regional data can be biased themselves, comparing them

  6. The nature of GPS differential receiver bias variability: An examination in the polar cap region

    NASA Astrophysics Data System (ADS)

    Themens, David R.; Jayachandran, P. T.; Langley, Richard B.

    2015-09-01

    While modern GPS receiver differential code bias estimation techniques have become highly refined, they still demonstrate unphysical behavior, namely, notable solar cycle variability. This study investigates the nature of these seasonal and solar cycle bias variabilities in the polar cap region using single-station bias estimation methods. It is shown that the minimization of standard deviation bias estimation technique is linearly dependent on the user's choice of shell height, where the sensitivity of this dependence varies significantly from 1 total electron content unit (1 TECU = 1016 el m-2) per 4000 km in solar minimum winter to in excess of 1 TECU per 90 km during solar maximum summer. Using an ionosonde, we find appreciable shell height variability resulting in bias variabilities of up to 2 TECU. Comparing northward face Resolute Incoherent Scatter Radar (RISR-N) measurements to a collocated GPS station, we find that RISR-derived GPS receiver biases vary seasonally but not with solar cycle. RMS differences between bias estimation methods and observation between 2009 and 2013 were found to range from 2.7 TECU to 3.4 TECU, depending on method. To account for the erroneous solar cycle variability of standard bias estimation approaches, we linearly fit these biases to sunspot number, removing the trend. RMS errors after sunspot detrending these biases are reduced to 1.91 TECU. Also, these ISR-derived and sunspot-detrended biases are fit to ambient temperature, where a significant correlation is found. By using these temperature-fitted biases we further reduce RMS errors to 1.66 TECU. These results can be taken as further evidence of temperature-dependent dispersion in the GPS cabling and antenna hardware.

  7. Gender bias in autoimmunity is influenced by microbiota.

    PubMed

    Yurkovetskiy, Leonid; Burrows, Michael; Khan, Aly A; Graham, Laura; Volchkov, Pavel; Becker, Lev; Antonopoulos, Dionysios; Umesaki, Yoshinori; Chervonsky, Alexander V

    2013-08-22

    Gender bias and the role of sex hormones in autoimmune diseases are well established. In specific pathogen-free nonobese diabetic (NOD) mice, females have 1.3-4.4 times higher incidence of type 1 diabetes (T1D). Germ-free (GF) mice lost the gender bias (female-to-male ratio 1.1-1.2). Gut microbiota differed in males and females, a trend reversed by male castration, confirming that androgens influence gut microbiota. Colonization of GF NOD mice with defined microbiota revealed that some, but not all, lineages overrepresented in male mice supported a gender bias in T1D. Although protection of males did not correlate with blood androgen concentration, hormone-supported expansion of selected microbial lineages may work as a positive-feedback mechanism contributing to the sexual dimorphism of autoimmune diseases. Gene-expression analysis suggested pathways involved in protection of males from T1D by microbiota. Our results favor a two-signal model of gender bias, in which hormones and microbes together trigger protective pathways.

  8. Types of Research Bias Encountered in IR.

    PubMed

    Gabr, Ahmed; Kallini, Joseph Ralph; Desai, Kush; Hickey, Ryan; Thornburg, Bartley; Kulik, Laura; Lewandowski, Robert J; Salem, Riad

    2016-04-01

    Bias is a systemic error in studies that leads to inaccurate deductions. Relevant biases in the field of IR and interventional oncology were identified after reviewing articles published in the Journal of Vascular and Interventional Radiology and CardioVascular and Interventional Radiology. Biases cited in these articles were divided into three categories: preinterventional (health care access, participation, referral, and sample biases), periinterventional (contamination, investigator, and operator biases), and postinterventional (guarantee-time, lead time, loss to follow-up, recall, and reporting biases). Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  9. Trends In Satellite Communication

    NASA Technical Reports Server (NTRS)

    Poley, William A.; Stevens, Grady H.; Stevenson, Steven M.; Lekan, Jack; Arth, Clifford H.; Hollansworth, James E.; Miller, Edward F.

    1988-01-01

    Report assesses trends in satellite communication from present to year 2010. Examines restrictions imposed by limited spectrum resource and technology needs created by trends. Personal communications, orbiting switchboards, and videophones foreseen.

  10. Marketing Trends to Watch

    ERIC Educational Resources Information Center

    Circle, Alison

    2009-01-01

    This article identifies 13 cultural trends that libraries can turn into opportunites to reach patrons. These trends include: Twitter, online reputation management, value added content, mobile marketing, and emotional connection.

  11. Marketing Trends to Watch

    ERIC Educational Resources Information Center

    Circle, Alison

    2009-01-01

    This article identifies 13 cultural trends that libraries can turn into opportunites to reach patrons. These trends include: Twitter, online reputation management, value added content, mobile marketing, and emotional connection.

  12. Heroin: Statistics and Trends

    MedlinePlus

    ... Emerging Trends and Alerts Alcohol Club Drugs Cocaine Hallucinogens Heroin Inhalants Marijuana MDMA (Ecstasy/Molly) Methamphetamine Opioids ... Emerging Trends and Alerts Alcohol Club Drugs Cocaine Hallucinogens Heroin Inhalants Marijuana MDMA (Ecstasy/Molly) Methamphetamine Opioids ...

  13. Trends in Education.

    ERIC Educational Resources Information Center

    School Planning & Management, 2002

    2002-01-01

    Several architects, planners, administrators, and contractors answer questions about trends related to school construction, interior design, business, security, and technology. Trends concern funding issues, specialized designs, planning for safety, technological integration, and equity in services. (EV)

  14. Trends in Education.

    ERIC Educational Resources Information Center

    School Planning & Management, 2002

    2002-01-01

    Several architects, planners, administrators, and contractors answer questions about trends related to school construction, interior design, business, security, and technology. Trends concern funding issues, specialized designs, planning for safety, technological integration, and equity in services. (EV)

  15. Variable-bias coin tossing

    SciTech Connect

    Colbeck, Roger; Kent, Adrian

    2006-03-15

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT.

  16. Variable-bias coin tossing

    NASA Astrophysics Data System (ADS)

    Colbeck, Roger; Kent, Adrian

    2006-03-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT.

  17. Belief bias and relational reasoning.

    PubMed

    Roberts, Maxwell J; Sykes, Elizabeth D A

    2003-01-01

    When people evaluate categorical syllogisms, they tend to reject unbelievable conclusions and accept believable ones irrespective of their validity. Typically, this effect is particularly marked for invalid conclusions that are possible, but do not necessarily follow, given the premises. However, smaller believability effects can also be detected for other types of conclusion. Three experiments are reported here, in which an attempt was made to determine whether belief bias effects can manifest themselves on the relational inference task. Subjects evaluated the validity of conclusions such as William the Conqueror was king after the Pyramids were built (temporal task) or Manchester is north of Bournemouth (spatial task) with respect to their premises. All of the major findings for equivalent categorical syllogism tasks were replicated. However, the overall size of the main effect of believability appears to be related to task presentation, a phenomenon not previously identified for categorical syllogisms and which current theories of belief bias have difficulty explaining.

  18. Touch Precision Modulates Visual Bias.

    PubMed

    Misceo, Giovanni F; Jones, Maurice D

    2017-08-29

    The sensory precision hypothesis holds that different seen and felt cues about the size of an object resolve themselves in favor of the more reliable modality. To examine this precision hypothesis, 60 college students were asked to look at one size while manually exploring another unseen size either with their bare fingers or, to lessen the reliability of touch, with their fingers sleeved in rigid tubes. Afterwards, the participants estimated either the seen size or the felt size by finding a match from a visual display of various sizes. Results showed that the seen size biased the estimates of the felt size when the reliability of touch decreased. This finding supports the interaction between touch reliability and visual bias predicted by statistically optimal models of sensory integration.

  19. Mindfulness reduces the correspondence bias.

    PubMed

    Hopthrow, Tim; Hooper, Nic; Mahmood, Lynsey; Meier, Brian P; Weger, Ulrich

    2017-03-01

    The correspondence bias (CB) refers to the idea that people sometimes give undue weight to dispositional rather than situational factors when explaining behaviours and attitudes. Three experiments examined whether mindfulness, a non-judgmental focus on the present moment, could reduce the CB. Participants engaged in a brief mindfulness exercise (the raisin task), a control task, or an attention to detail task before completing a typical CB measure involving an attitude-attribution paradigm. The results indicated that participants in the mindfulness condition experienced a significant reduction in the CB compared to participants in the control or attention to detail conditions. These results suggest that mindfulness training can play a unique role in reducing social biases related to person perception.

  20. Gender Bias in SAT Items.

    ERIC Educational Resources Information Center

    Loewen, James W.; And Others

    Sex-related bias on the Scholastic Aptitude Test (SAT) was studied in a sample of 1,112 students in SAT coaching classes who took the SAT. Of these, 1,028 answered an additional questionnaire (Appendix A of this report) about high school grade point average, perceived abilities, and background. Almost all of the subjects were 11th graders (97.8%),…

  1. Self regulating body bias generator

    NASA Technical Reports Server (NTRS)

    Hass, Kenneth (Inventor)

    2004-01-01

    The back bias voltage on a functional circuit is controlled through a closed loop process. A delay element receives a clock pulse and produces a delay output. The delay element is advantageously constructed of the same materials as the functional circuit so that the aging and degradation of the delay element parallels the degradation of the functional circuit. As the delay element degrades, the transistor switching time increases, increasing the time delay of the delay output. An AND gate compares a clock pulse to an output pulse of the delay element, the AND output forming a control pulse. A duty cycle of the control pulse is determined by the delay time between the clock pulse and the delay element output. The control pulse is received at the input of a charge pump. The charge pump produces a back bias voltage which is then applied to the delay element and to the functional circuit. If the time delay produced by the delay element exceeds the optimal delay, the duty cycle of the control pulse is shortened, and the back bias voltage is lowered, thereby increasing the switching speed of the transistors in the delay element and reducing the time delay. If the throughput of the delay element is too fast, the duty cycle of the control pulse is lengthened, raising the back bias voltage produced by the charge pump. This, in turn, lowers the switching speed of the transistors in both the delay element and the functional circuit. The slower switching speed in the delay element increases time delay. In this manner, the switching speed of the delay element, and of the functional circuit, is maintained at a constant level over the life of the circuit.

  2. Good practices for quantitative bias analysis.

    PubMed

    Lash, Timothy L; Fox, Matthew P; MacLehose, Richard F; Maldonado, George; McCandless, Lawrence C; Greenland, Sander

    2014-12-01

    Quantitative bias analysis serves several objectives in epidemiological research. First, it provides a quantitative estimate of the direction, magnitude and uncertainty arising from systematic errors. Second, the acts of identifying sources of systematic error, writing down models to quantify them, assigning values to the bias parameters and interpreting the results combat the human tendency towards overconfidence in research results, syntheses and critiques and the inferences that rest upon them. Finally, by suggesting aspects that dominate uncertainty in a particular research result or topic area, bias analysis can guide efficient allocation of sparse research resources. The fundamental methods of bias analyses have been known for decades, and there have been calls for more widespread use for nearly as long. There was a time when some believed that bias analyses were rarely undertaken because the methods were not widely known and because automated computing tools were not readily available to implement the methods. These shortcomings have been largely resolved. We must, therefore, contemplate other barriers to implementation. One possibility is that practitioners avoid the analyses because they lack confidence in the practice of bias analysis. The purpose of this paper is therefore to describe what we view as good practices for applying quantitative bias analysis to epidemiological data, directed towards those familiar with the methods. We focus on answering questions often posed to those of us who advocate incorporation of bias analysis methods into teaching and research. These include the following. When is bias analysis practical and productive? How does one select the biases that ought to be addressed? How does one select a method to model biases? How does one assign values to the parameters of a bias model? How does one present and interpret a bias analysis?. We hope that our guide to good practices for conducting and presenting bias analyses will encourage

  3. SEASAT altimeter timing bias estimation

    NASA Astrophysics Data System (ADS)

    Marsh, J. G.; Williamson, R. G.

    1982-04-01

    The calibration of the altimeter observation time tags to the millisecond level of accuracy is fundamental to the processing of the data. Initial analyses of the SEASAT altimeter data indicated the presence of a time calibration bias which produced altimeter measurement errors in excess of a meter. A technique has been developed for the solution of the time tag bias based upon the analysis of sea surface height discrepancies at ground track intersections. This technique has permitted very good separation of the dominant once per revolution ephemeris error, which amounts to about 1.5 m rms, from the timing error signature. Furthermore, the technique does not depend upon the availability of precise geoid data. The application of this technique to a global set of SEASAT altimeter data covering the time period of July 28-August 9, 1978, has resulted in a value of -81.0±2 ms for the time tag bias. This value agrees to within 2.9 ms of the value derived at the University of Texas from a similar analysis of the altimeter data. Furthermore, these values corroborate the revised value of -79.4 ms derived at NASA/Wallops Flight Center and the Johns Hopkins University/Applied Physics Lab from a reexamination of the internal instrument time delays. The modeling of oceanic tides and the orbit computations are the major error sources in these analyses.

  4. Opinion dynamics with confirmation bias.

    PubMed

    Allahverdyan, Armen E; Galstyan, Aram

    2014-01-01

    Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect-when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) -and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development.

  5. Generalization of the FRAM's Bias

    SciTech Connect

    Duc T. Vo

    2005-10-01

    The Fixed-Energy Response-Function Analysis with Multiple Efficiency (FRAM) code was developed at Los Alamos National Laboratory to measure the gamma-ray spectrometry of the isotopic composition of plutonium, uranium, and other actinides. Its reported uncertainties of the results come from the propagation of the statistics in the peak areas only. No systematic error components are included in the reported uncertainties. We have done several studies and found that the FRAM's statistical precision can be reasonably represented by its reported uncertainties. The FRAM's biases or systematic uncertainties can come from a variety of sources and can be difficult to determine. We carefully examined the FRAM analytical results of the archival plutonium data and of the data specifically acquired for this isotopic uncertainty analysis project and found the relationship between the bias and other parameters. We worked out the equations representing the biases of the measured isotopes from each measurement using the internal parameters in the spectrum such as peak resolution and shape, region of analysis, and burnup (for plutonium) or enrichment (for uranium).

  6. Galaxy formation and physical bias

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Ostriker, Jeremiah P.

    1992-01-01

    We have supplemented our code, which computes the evolution of the physical state of a representative piece of the universe to include, not only the dynamics of dark matter (with a standard PM code), and the hydrodynamics of the gaseous component (including detailed collisional and radiative processes), but also galaxy formation on a heuristic but plausible basis. If, within a cell the gas is Jeans' unstable, collapsing, and cooling rapidly, it is transformed to galaxy subunits, which are then followed with a collisionless code. After grouping them into galaxies, we estimate the relative distributions of galaxies and dark matter and the relative velocities of galaxies and dark matter. In a large scale CDM run of 80/h Mpc size with 8 x 10 exp 6 cells and dark matter particles, we find that physical bias b is on the 8/h Mpc scale is about 1.6 and increases towards smaller scales, and that velocity bias is about 0.8 on the same scale. The comparable HDM simulation is highly biased with b = 2.7 on the 8/h Mpc scale. Implications of these results are discussed in the light of the COBE observations which provide an accurate normalization for the initial power spectrum. CDM can be ruled out on the basis of too large a predicted small scale velocity dispersion at greater than 95 percent confidence level.

  7. Response bias in plaintiffs' histories.

    PubMed

    Lees-Haley, P R; Williams, C W; Zasler, N D; Marguilies, S; English, L T; Stevens, K B

    1997-11-01

    This study investigated response bias in self-reported history of factors relevant to the assessment of traumatic brain injury, toxic brain injury and related emotional distress. Response bias refers to systematic error in self-report data. A total of 446 subjects (comprising 131 litigating and 315 non-litigating adults from five locations in the United States) completed a symptom questionnaire. Data were obtained from university faculty and students, from patients in clinics specializing in physiatry neurology, and family medicine, and from plaintiffs undergoing forensic neuropsychological evaluations. Comparisons were made for litigant and non litigant ratings of their past and current cognitive and emotional functioning, including life in general, ability to concentrate, memory, depression, anxiety, alcohol, drugs, ability to work or attend school, irritability, headaches, confusion, self-esteem, and fatigue. Although there is no basis for hypothesizing plaintiffs to be healthier than the general population, plaintiffs rated their pre-injury functioning superior to non-plaintiffs. These findings suggest that response biases need to be taken into account by forensic examiners when relying on litigants' self-reports of pre-injury status.

  8. Galaxy formation and physical bias

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Ostriker, Jeremiah P.

    1992-01-01

    We have supplemented our code, which computes the evolution of the physical state of a representative piece of the universe to include, not only the dynamics of dark matter (with a standard PM code), and the hydrodynamics of the gaseous component (including detailed collisional and radiative processes), but also galaxy formation on a heuristic but plausible basis. If, within a cell the gas is Jeans' unstable, collapsing, and cooling rapidly, it is transformed to galaxy subunits, which are then followed with a collisionless code. After grouping them into galaxies, we estimate the relative distributions of galaxies and dark matter and the relative velocities of galaxies and dark matter. In a large scale CDM run of 80/h Mpc size with 8 x 10 exp 6 cells and dark matter particles, we find that physical bias b is on the 8/h Mpc scale is about 1.6 and increases towards smaller scales, and that velocity bias is about 0.8 on the same scale. The comparable HDM simulation is highly biased with b = 2.7 on the 8/h Mpc scale. Implications of these results are discussed in the light of the COBE observations which provide an accurate normalization for the initial power spectrum. CDM can be ruled out on the basis of too large a predicted small scale velocity dispersion at greater than 95 percent confidence level.

  9. Adjusting urban bias in the regional mean surface temperature series of South Korea, 1968-99

    NASA Astrophysics Data System (ADS)

    Choi, Youngeun; Jung, Hyun-Sook; Nam, Kyung-Yeub; Kwon, Won-Tae

    2003-04-01

    The purpose of this paper is to produce a higher quality regional surface temperature series by removing urban biases in South Korean surface temperatures using statistical procedures. Monthly mean temperatures for 16 stations were obtained for a period of 32 years (1968-99). Each station is defined as an urban station or a rural station. Urban (rural) stations are defined as those that have population densities greater (less) than 1000 persons per squared kilometer in 1995. Ten urban stations and six rural stations are identified. Again, urban stations are subdivided into two groups according to whether their population totals exceed one million to examine magnitude changes of urban biases with the size of urban areas. Estimates of urban bias magnitude are calculated by averaging the difference between each urban station and every rural station. Estimates of mean urban bias magnitude (u-r) are calculated by averaging the yearly urban bias estimates. Estimates of the urban trend (Tu-r) are obtained by differencing period means (by doubling the differences obtained between yearly estimates averaged over two 16 year periods, 1968-83 and 1984-99). For annual or seasonal mean temperature Ti, the adjusted temperature Ti is determined. As all estimates of u-r are greater than zero, it suggests that temperatures in urban stations are warmer than those in rural stations. Estimates of the annual mean magnitude of urban bias range from 0.35 °C for smaller urban stations to 0.50 °C for large urban stations. Also, all estimates of Tu-r are positive, indicating an increasing trend in the urban bias time series. Seasonal variations are found in u-r and Tu-r. After adjusting the urban bias, an increasing trend in surface temperature series is still evident.

  10. Tree demography dominates long-term growth trends inferred from tree rings.

    PubMed

    Brienen, Roel J W; Gloor, Manuel; Ziv, Guy

    2017-02-01

    Understanding responses of forests to increasing CO2 and temperature is an important challenge, but no easy task. Tree rings are increasingly used to study such responses. In a recent study, van der Sleen et al. (2014) Nature Geoscience, 8, 4 used tree rings from 12 tropical tree species and find that despite increases in intrinsic water use efficiency, no growth stimulation is observed. This challenges the idea that increasing CO2 would stimulate growth. Unfortunately, tree ring analysis can be plagued by biases, resulting in spurious growth trends. While their study evaluated several biases, it does not account for all. In particular, one bias may have seriously affected their results. Several of the species have recruitment patterns, which are not uniform, but clustered around one specific year. This results in spurious negative growth trends if growth rates are calculated in fixed size classes, as 'fast-growing' trees reach the sampling diameter earlier compared to slow growers and thus fast growth rates tend to have earlier calendar dates. We assessed the effect of this 'nonuniform age bias' on observed growth trends and find that van der Sleen's conclusions of a lack of growth stimulation do not hold. Growth trends are - at least partially - driven by underlying recruitment or age distributions. Species with more clustered age distributions show more negative growth trends, and simulations to estimate the effect of species' age distributions show growth trends close to those observed. Re-evaluation of the growth data and correction for the bias result in significant positive growth trends of 1-2% per decade for the full period, and 3-7% since 1950. These observations, however, should be taken cautiously as multiple biases affect these trend estimates. In all, our results highlight that tree ring studies of long-term growth trends can be strongly influenced by biases if demographic processes are not carefully accounted for. © 2016 The Authors. Global Change

  11. The Probability Distribution for a Biased Spinner

    ERIC Educational Resources Information Center

    Foster, Colin

    2012-01-01

    This article advocates biased spinners as an engaging context for statistics students. Calculating the probability of a biased spinner landing on a particular side makes valuable connections between probability and other areas of mathematics. (Contains 2 figures and 1 table.)

  12. The Nonverbal Transmission of Intergroup Bias: A Model of Bias Contagion with Implications for Social Policy

    PubMed Central

    Weisbuch, Max; Pauker, Kristin

    2013-01-01

    Social and policy interventions over the last half-century have achieved laudable reductions in blatant discrimination. Yet members of devalued social groups continue to face subtle discrimination. In this article, we argue that decades of anti-discrimination interventions have failed to eliminate intergroup bias because such bias is contagious. We present a model of bias contagion in which intergroup bias is subtly communicated through nonverbal behavior. Exposure to such nonverbal bias “infects” observers with intergroup bias. The model we present details two means by which nonverbal bias can be expressed—either as a veridical index of intergroup bias or as a symptom of worry about appearing biased. Exposure to this nonverbal bias can increase perceivers’ own intergroup biases through processes of implicit learning, informational influence, and normative influence. We identify critical moderators that may interfere with these processes and consequently propose several social and educational interventions based on these moderators. PMID:23997812

  13. Expectancy bias mediates the link between social anxiety and memory bias for social evaluation

    PubMed Central

    Caouette, Justin D.; Ruiz, Sarah K.; Lee, Clinton C.; Anbari, Zainab; Schriber, Roberta A.; Guyer, Amanda E.

    2014-01-01

    Social anxiety (SA) involves a multitude of cognitive symptoms related to fear of evaluation, including expectancy and memory biases. We examined whether memory biases are influenced by expectancy biases for social feedback in SA. We hypothesized that, faced with a socially evaluative event, people with higher SA would show a negative expectancy bias for future feedback. Furthermore, we predicted that memory bias for feedback in SA would be mediated by expectancy bias. Ninety-four undergraduate students (55 women, mean age = 19.76 years) underwent a two-visit task that measured expectations about (Visit 1) and memory of (Visit 2) feedback from unknown peers. Results showed that higher levels of SA were associated with negative expectancy bias. An indirect relationship was found between SA and memory bias that was mediated by expectancy bias. The results suggest that expectancy biases are in the causal path from SA to negative memory biases for social evaluation. PMID:25252925

  14. Gas composition influence on ion energy distribution functions in an industrial ICP reactor with biased cathode

    NASA Astrophysics Data System (ADS)

    Peterson, David; Shannon, Steven; Coumou, David; White, Scott

    2016-09-01

    An industrial ICP reactor consisting of a top planar coil and RF biased lower electrode has been characterized using a hairpin resonator probe and gridded ion energy analyzer to measure electron density in the bulk plasma and ion energy distribution function (IEDF) at the surface of the biased cathode. Argon and oxygen were run at constant total flow with 20mTorr downstream pressure control with varying flow ratios between the two gases ranging from 0% to 100% oxygen content. ICP and bias power were adjusted to maintain constant electron density and sheath bias over this mixing matrix at four different setpoints reflecting high density / high bias, high density / low bias, low density / high bias, and low density / low bias. Although the fundamental parameters governing RF sheath behavior were held constant, several trends in ion energy distribution are observed with respect to gas composition (aside from the obvious influence of ion mass) that show considerable variation in measured IEDF particularly that can be attributed to ion collisions in the sheath as well as gas heating variation due to gas composition.

  15. Goals and strategies for estimating trends in landbird abundance

    Treesearch

    Jonathan Bart; Kenneth P. Burnham; Erica H. Dunn; Charles M. Francis; C. John Ralph

    2004-01-01

    Reliable estimates of trends in population size are critical to effective management of landbirds. We propose a standard for considering that landbird populations are adequately monitored: 80% power to detect a 50% decline occurring within 20 years, using a 2-tailed test and a significance level of 0.10, and incorporating effects of potential bias. Our standard also...

  16. Isotopic biases for actinide-only burnup credit

    SciTech Connect

    Rahimi, M.; Lancaster, D.; Hoeffer, B.; Nichols, M.

    1997-04-01

    The primary purpose of this paper is to present the new methodology for establishing bias and uncertainty associated with isotopic prediction in spent fuel assemblies for burnup credit analysis. The analysis applies to the design of criticality control systems for spent fuel casks. A total of 54 spent fuel samples were modeled and analyzed using the Shielding Analyses Sequence (SAS2H). Multiple regression analysis and a trending test were performed to develop isotopic correction factors for 10 actinide burnup credit isotopes. 5 refs., 1 tab.

  17. A new inequality? Privatisation, urban bias, migration and medical tourism.

    PubMed

    Connell, John

    2011-01-01

    Access to health care in developing countries, the main destinations of medical tourists, is notoriously uneven, and often becoming more so. Medical tourism, urban bias and privatisation have combined to exacerbate this trend. This is exemplified in both Thailand and India, where regional areas have been disadvantaged by the migration of health-care workers to hospitals focusing on medical tourism, neo-liberal national financial provision for medical tourism (and related tourism campaigns) and evidence of trickle-down gains is lacking. Medical tourism challenges rather than complements local health care providers, distorts national health care systems, and raises critical national economic, ethical and social questions.

  18. Integrating Implicit Bias into Counselor Education

    ERIC Educational Resources Information Center

    Boysen, Guy A.

    2010-01-01

    The author reviews the empirical and theoretical literature on implicit bias as it relates to counselor education. Counselor educators can integrate implicit bias into the concepts of multicultural knowledge, awareness, and skill. Knowledge about implicit bias includes its theoretical explanation, measurement, and impact on counseling. Awareness…

  19. Understanding Errors, Biases that Can Affect Journalists.

    ERIC Educational Resources Information Center

    Stocking, S. Holly; Gross, Paget H.

    1989-01-01

    Outlines some of the errors and biases in thinking that psychologists have documented in recent years, including the eyewitness fallacy, underutilization of statistics, confirmation bias, misperceptions of risk, sample errors and biases, and misunderstanding of regression. Argues that journalism educators need to bring these to the attention of…

  20. Using Newspapers to Study Media Bias.

    ERIC Educational Resources Information Center

    Kirman, Joseph M.

    1992-01-01

    Suggests that students can learn to recognize media bias by studying media reports of current events or historical topics. Describes a study unit using media coverage of the second anniversary of the Palestinian uprising against Israel. Discusses lesson objectives, planning, defining bias teaching procedures, and criteria for determining bias. (DK)

  1. Gender Bias: Recent Research and Interventions.

    ERIC Educational Resources Information Center

    New Jersey Research Bulletin, 1996

    1996-01-01

    This annotated bibliography lists 14 publications about recent research on gender bias and interventions to reduce gender bias in schools. The bibliography is divided into two sections: current research and intervention. The first includes descriptions of studies examining the following topics: gender bias in U.S. schools and its effects;…

  2. Outcome-Reporting Bias in Education Research

    ERIC Educational Resources Information Center

    Pigott, Therese D.; Valentine, Jeffrey C.; Polanin, Joshua R.; Williams, Ryan T.; Canada, Dericka D.

    2013-01-01

    Outcome-reporting bias occurs when primary studies do not include information about all outcomes measured in a study. When studies omit findings on important measures, efforts to synthesize the research using systematic review techniques will be biased and interpretations of individual studies will be incomplete. Outcome-reporting bias has been…

  3. Attentional Bias for Exercise-Related Images

    ERIC Educational Resources Information Center

    Berry, Tanya R.; Spence, John C.; Stolp, Sean M.

    2011-01-01

    This research examined attentional bias toward exercise-related images using a visual probe task. It was hypothesized that more-active participants would display attentional bias toward the exercise-related images. The results showed that men displayed attentional bias for the exercise images. There was a significant interaction of activity level…

  4. Attentional Bias for Exercise-Related Images

    ERIC Educational Resources Information Center

    Berry, Tanya R.; Spence, John C.; Stolp, Sean M.

    2011-01-01

    This research examined attentional bias toward exercise-related images using a visual probe task. It was hypothesized that more-active participants would display attentional bias toward the exercise-related images. The results showed that men displayed attentional bias for the exercise images. There was a significant interaction of activity level…

  5. Eliminating bias in satellite retrievals of sea surface temperature

    NASA Astrophysics Data System (ADS)

    Merchant, Christopher John

    Sea surface temperature (SST) is a critical parameter for climate research, and needs to be measured with an absolute accuracy of ~0.3 K (average over ~100 km scale on a weekly to monthly time scale) and with a long term stability of 0.1 K per decade. These stringent requirements present a formidable challenge to satellite based SST measurement. The most promising satellite radiometer is the ATSR (and successors), but bias and spurious trends have arisen in the ATSR SST retrieval process. Eliminating such retrieval bias is the focus of this thesis. SSTs derived from the ATSR using the prelaunch retrieval scheme are biased by up to -1.5 K by stratospheric aerosol from the eruption of Mount Pinatubo shortly before launch. An "aerosol-robust" retrieval scheme is derived which has no detectable aerosol- related bias. Another bias of up to 0.5 K arising from a deficiency of the radiative transfer model used to develop the prelaunch retrieval scheme is resolved by implementing an updated parameterisation of water vapour continuum absorption. The new SSTs are shown to have an accuracy better than 0.3 K (error in a single retrieval over a -20 km spatial scale) and to be robust to aerosol effects, by a validation exercise against buoys measuring SST in situ. The validation data consist of 620 satellite-buoy coincidences in the tropical Pacific between September 1991 and May 1992, a region and period associated with high loadings of stratospheric aerosol and tropospheric water vapour. This is the first validation exercise to correct for the effects of the difference between bulk SSTs (measured by buoys) and skin SSTs (measured radiometrically). The factor now limiting accuracy is residual cloud contamination. The new retrieval scheme has been adopted for the reprocessing of all archived ATSR data to SST.

  6. Sources and implications of bias and uncertainty in a century of US wildfire activity data

    Treesearch

    Karen C. Short

    2015-01-01

    Analyses to identify and relate trends in wildfire activity to factors such as climate, population, land use or land cover and wildland fire policy are increasingly popular in the United States. There is a wealth of US wildfire activity data available for such analyses, but users must be aware of inherent reporting biases, inconsistencies and uncertainty in the data in...

  7. Opinion Dynamics with Confirmation Bias

    PubMed Central

    Allahverdyan, Armen E.; Galstyan, Aram

    2014-01-01

    Background Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. Methodology/Principal Findings We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect–when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) –and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. Conclusions The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development. PMID:25007078

  8. Estimating the effect of nonresponse bias in a survey of hospital organizations.

    PubMed

    Lewis, Emily F; Hardy, Maryann; Snaith, Beverly

    2013-09-01

    Nonresponse bias in survey research can result in misleading or inaccurate findings and assessment of nonresponse bias is advocated to determine response sample representativeness. Four methods of assessing nonresponse bias (analysis of known characteristics of a population, subsampling of nonresponders, wave analysis, and linear extrapolation) were applied to the results of a postal survey of U.K. hospital organizations. The purpose was to establish whether validated methods for assessing nonresponse bias at the individual level can be successfully applied to an organizational level survey. The aim of the initial survey was to investigate trends in the implementation of radiographer abnormality detection schemes, and a response rate of 63.7% (325/510) was achieved. This study identified conflicting trends in the outcomes of analysis of nonresponse bias between the different methods applied and we were unable to validate the continuum of resistance theory as applied to organizational survey data. Further work is required to ensure established nonresponse bias analysis approaches can be successfully applied to organizational survey data. Until then, it is suggested that a combination of methods should be used to enhance the rigor of survey analysis.

  9. Uncertainty in ocean mass trends from GRACE

    NASA Astrophysics Data System (ADS)

    Quinn, Katherine J.; Ponte, Rui M.

    2010-05-01

    Ocean mass, together with steric sea level, are the key components of total observed sea level change. Monthly observations from the Gravity Recovery and Climate Experiment (GRACE) can provide estimates of the ocean mass component of the sea level budget, but full use of the data requires a detailed understanding of its errors and biases. We have examined trends in ocean mass calculated from 6 yr of GRACE data and found differences of up to 1 mmyr-1 between estimates derived from different GRACE processing centre solutions. In addition, variations in post-processing masking and filtering procedures required to convert the GRACE data into ocean mass lead to trend differences of up to 0.5 mmyr-1. Necessary external model adjustments add to these uncertainties, with reported postglacial rebound corrections differing by as much as 1 mmyr-1. Disagreement in the regional trends between the GRACE processing centres is most noticeably in areas south of Greenland, and in the southeast and northwest Pacific Ocean. Non-ocean signals, such as in the Indian Ocean due to the 2004 Sumatran-Andean earthquake, and near Greenland and West Antarctica due to land signal leakage, can also corrupt the ocean trend estimates. Based on our analyses, formal errors may not capture the true uncertainty in either regional or global ocean mass trends derived from GRACE.

  10. Uncertainty in ocean mass trends from GRACE

    NASA Astrophysics Data System (ADS)

    Quinn, K. J.; Ponte, R. M.

    2009-12-01

    Ocean mass, together with steric sea level, are the key components of total observed sea level rise. Monthly observations from the Gravity Recovery and Climate Experiment (GRACE) can provide estimates of the ocean mass component of the sea level budget, but full use of the data requires a detailed understanding of its errors and biases. We have examined trends in ocean mass calculated from six years of GRACE data and found differences of up to 1 mm/yr between estimates derived from different GRACE processing center solutions. In addition, variations in post-processing masking and filtering procedures required to convert the GRACE data into ocean mass lead to trend differences of up to 0.5 mm/yr. Necessary external model adjustments add to these uncertainties, with reported post-glacial rebound corrections differing by as much as 1 mm/yr. Disagreement in the regional trends between the GRACE processing centers is most noticeable in areas south of Greenland, and in the southeast and northwest Pacific Ocean. Non-ocean signals, such as in the Indian Ocean due to the 2004 Sumatran-Andean earthquake, and near Greenland and West Antarctica due to land signal leakage, can also corrupt the ocean trend estimates. Based on our analyses, formal errors may not capture the true uncertainty in either regional or global ocean mass trends derived from GRACE.

  11. NASA trend analysis procedures

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This publication is primarily intended for use by NASA personnel engaged in managing or implementing trend analysis programs. 'Trend analysis' refers to the observation of current activity in the context of the past in order to infer the expected level of future activity. NASA trend analysis was divided into 5 categories: problem, performance, supportability, programmatic, and reliability. Problem trend analysis uncovers multiple occurrences of historical hardware or software problems or failures in order to focus future corrective action. Performance trend analysis observes changing levels of real-time or historical flight vehicle performance parameters such as temperatures, pressures, and flow rates as compared to specification or 'safe' limits. Supportability trend analysis assesses the adequacy of the spaceflight logistics system; example indicators are repair-turn-around time and parts stockage levels. Programmatic trend analysis uses quantitative indicators to evaluate the 'health' of NASA programs of all types. Finally, reliability trend analysis attempts to evaluate the growth of system reliability based on a decreasing rate of occurrence of hardware problems over time. Procedures for conducting all five types of trend analysis are provided in this publication, prepared through the joint efforts of the NASA Trend Analysis Working Group.

  12. Magnetoelectric switching of exchange bias.

    PubMed

    Borisov, Pavel; Hochstrat, Andreas; Chen, Xi; Kleemann, Wolfgang; Binek, Christian

    2005-03-25

    The perpendicular exchange bias field, H(EB), of the magnetoelectric heterostructure Cr2O3(111)/(Co/Pt)(3) changes sign after field cooling to below the Néel temperature of Cr2O3 in either parallel or antiparallel axial magnetic and electric freezing fields. The switching of H(EB) is explained by magnetoelectrically induced antiferromagnetic single domains which extend to the interface, where the direction of their end spins controls the sign of H(EB). Novel applications in magnetoelectronic devices seem possible.

  13. Charge amplifier with bias compensation

    DOEpatents

    Johnson, Gary W.

    2002-01-01

    An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

  14. Recent Research Trends in Meta-analysis.

    PubMed

    Shin, In-Soo

    2017-06-01

    The use of meta-analysis (MA), which is placed on top of the evidence hierarchy, in studies has been increasing exponentially. MA has three effect size families. Using the category of effect size families, this paper introduces the important points in the MA process and highlights the recent research trends in this field, such as network MA, meta-analytic structural equation modeling, and diagnostic test accuracy MA. Several reporting standards were established for primary studies and MA. The critical assessment reviews demonstrated that the current quality of nursing MA reporting was low. The problematic areas of the current nursing MA include study search, study selection, risk of bias, publication bias, and additional analysis based on quality assessment. Directions for future research are also presented in this paper. Copyright © 2017. Published by Elsevier B.V.

  15. Challenges in bias correcting climate change simulations

    NASA Astrophysics Data System (ADS)

    Maraun, Douglas; Shepherd, Ted; Zappa, Giuseppe; Gutierrez, Jose; Widmann, Martin; Hagemann, Stefan; Richter, Ingo; Soares, Pedro; Mearns, Linda

    2016-04-01

    Biases in climate model simulations - if these are directly used as input for impact models - will introduce further biases in subsequent impact simulations. In response to this issue, so-called bias correction methods have been developed to post-process climate model output. These methods are now widely used and a crucial component in the generation of high resolution climate change projections. Bias correction is conceptually similar to model output statistics, which has been successfully used for several decades in numerical weather prediction. Yet in climate science, some authors outrightly dismiss any form of bias correction. Starting from this seeming contradiction, we highlight differences between the two contexts and infer consequences and limitations for the applicability of bias correction to climate change projections. We first show that cross validation approaches successfully used to evaluate weather forecasts are fundamentally insufficient to evaluate climate change bias correction. We further demonstrate that different types of model mismatches with observations require different solutions, and some may not sensibly be mitigated. In particular we consider the influence of large-scale circulation biases, biases in the persistence of weather regimes, and regional biases caused by an insufficient representation of the flow-topography interaction. We conclude with a list of recommendations and suggestions for future research to reduce, to post-process, and to cope with climate model biases.

  16. Numeracy and framing bias in epilepsy.

    PubMed

    Choi, Hyunmi; Wong, John B; Mendiratta, Anil; Heiman, Gary A; Hamberger, Marla J

    2011-01-01

    Patients with epilepsy are frequently confronted with complex treatment decisions. Communicating treatment risks is often difficult because patients may have difficulty with basic statistical concepts (i.e., low numeracy) or might misconceive the statistical information based on the way information is presented, a phenomenon known as "framing bias." We assessed numeracy and framing bias in 95 adults with chronic epilepsy and explored cognitive correlates of framing bias. Compared with normal controls, patients with epilepsy had significantly poorer performance on the Numeracy scale (P=0.02), despite a higher level of education than normal controls (P<0.001). Compared with patients with higher numeracy, patients with lower numeracy were significantly more likely to exhibit framing bias. Abstract problem solving performance correlated with the degree of framing bias (r=0.631, P<0.0001), suggesting a relationship between aspects of executive functioning and framing bias. Poor numeracy and susceptibility framing bias place patients with epilepsy at risk for uninformed decisions.

  17. Characterizing dye bias in microarray experiments.

    PubMed

    Dobbin, K K; Kawasaki, E S; Petersen, D W; Simon, R M

    2005-05-15

    Spot intensity serves as a proxy for gene expression in dual-label microarray experiments. Dye bias is defined as an intensity difference between samples labeled with different dyes attributable to the dyes instead of the gene expression in the samples. Dye bias that is not removed by array normalization can introduce bias into comparisons between samples of interest. But if the bias is consistent across samples for the same gene, it can be corrected by proper experimental design and analysis. If the dye bias is not consistent across samples for the same gene, but is different for different samples, then removing the bias becomes more problematic, perhaps indicating a technical limitation to the ability of fluorescent signals to accurately represent gene expression. Thus, it is important to characterize dye bias to determine: (1) whether it will be removed for all genes by array normalization, (2) whether it will not be removed by normalization but can be removed by proper experimental design and analysis and (3) whether dye bias correction is more problematic than either of these and is not easily removable. We analyzed two large (each >27 arrays) tissue culture experiments with extensive dye swap arrays to better characterize dye bias. Indirect, amino-allyl labeling was used in both experiments. We found that post-normalization dye bias that is consistent across samples does appear to exist for many genes, and that controlling and correcting for this type of dye bias in design and analysis is advisable. The extent of this type of dye bias remained unchanged under a wide range of normalization methods (median-centering, various loess normalizations) and statistical analysis techniques (parametric, rank based, permutation based, etc.). We also found dye bias related to the individual samples for a much smaller subset of genes. But these sample-specific dye biases appeared to have minimal impact on estimated gene-expression differences between the cell lines.

  18. Effect of asymmetric molecule-electrode coupling and molecular bias on rectification in molecular junctions

    NASA Astrophysics Data System (ADS)

    Kaur, Rupan Preet; Sawhney, Ravinder Singh; Engles, Derick

    2016-12-01

    In this research work, we compare the rectification trends of two symmetrical and one asymmetrical molecular junction formed with gold and silver electrodes bridging benzenedithiol molecule. The origin of rectification is attributed to both molecular bias drop and asymmetric molecule-electrode coupling. The electronic transport properties are computed by using semi-empirical extended Huckel method combined with non-equilibrium Green's function framework. The results are fully rationalized by analysing the distribution of molecular orbitals with changing bias voltage, available density of states and area of transmission spectra spanned within bias window, transmission eigenstates and transmission pathways. We deduce through this work that the molecular rectification is not only the property of asymmetric molecule-metal coupling, but molecular bias also plays vital role in stemming asymmetric I- V characteristics. Our results suggest how to realize molecular rectification by using different electrode materials which act as Schottky barriers in molecular junctions that emulate p-n junction diode in semiconductor electronics.

  19. Information processing bias and pharmacotherapy outcome in older adults with generalized anxiety disorder.

    PubMed

    Steiner, Amanda R W; Petkus, Andrew J; Nguyen, Hoang; Wetherell, Julie Loebach

    2013-08-01

    Information processing bias was evaluated in a sample of 25 older adults with generalized anxiety disorder (GAD) over the course of 12 weeks of escitalopram pharmacotherapy. Using the CANTAB Affective Go/No Go test, treatment response (as measured by the Hamilton Anxiety Rating Scale, Penn State Worry Questionnaire, and Generalized Anxiety Disorder Severity Scale) was predicted from a bias score (i.e., difference score between response latencies for negative and positive words) using mixed-models regression. A more positive bias score across time predicted better response to treatment. Faster responses to positive words relative to negative words were associated with greater symptomatic improvement over time as reflected by scores on the GADSS. There was a trend toward significance for PSWQ scores and no significant effects related to HAMA outcomes. These preliminary findings offer further insights into the role of biased cognitive processing of emotional material in the manifestation of late-life anxiety symptoms.

  20. A review of bias flow liners for acoustic damping in gas turbine combustors

    NASA Astrophysics Data System (ADS)

    Lahiri, C.; Bake, F.

    2017-07-01

    The optimized design of bias flow liner is a key element for the development of low emission combustion systems in modern gas turbines and aero-engines. The research of bias flow liners has a fairly long history concerning both the parameter dependencies as well as the methods to model the acoustic behaviour of bias flow liners under the variety of different bias and grazing flow conditions. In order to establish an overview over the state of the art, this paper provides a comprehensive review about the published research on bias flow liners and modelling approaches with an extensive study of the most relevant parameters determining the acoustic behaviour of these liners. The paper starts with a historical description of available investigations aiming on the characterization of the bias flow absorption principle. This chronological compendium is extended by the recent and ongoing developments in this field. In a next step the fundamental acoustic property of bias flow liner in terms of the wall impedance is introduced and the different derivations and formulations of this impedance yielding the different published model descriptions are explained and compared. Finally, a parametric study reveals the most relevant parameters for the acoustic damping behaviour of bias flow liners and how this is reflected by the various model representations. Although the general trend of the investigated acoustic behaviour is captured by the different models fairly well for a certain range of parameters, in the transition region between the resonance dominated and the purely bias flow related regime all models lack the correct damping prediction. This seems to be connected to the proper implementation of the reactance as a function of bias flow Mach number.

  1. [Biases in the study of prognostic factors].

    PubMed

    Delgado-Rodríguez, M

    1999-01-01

    The main objective is to detail the main biases in the study of prognostic factors. Confounding bias is illustrated with social class, a prognostic factor still discussed. Within selection bias several cases are commented: response bias, specially frequent when the patients of a clinical trial are used; the shortcomings in the formation of an inception cohort; the fallacy of Neyman (bias due to the duration of disease) when the study begins with a cross-sectional study; the selection bias in the treatment of survivors for the different treatment opportunity of those living longer; the bias due to the inclusion of heterogeneous diagnostic groups; and the selection bias due to differential information losses and the use of statistical multivariate procedures. Within the biases during follow-up, an empiric rule to value the impact of the number of losses is given. In information bias the Will Rogers' phenomenon and the usefulness of clinical databases are discussed. Lastly, a recommendation against the use of cutoff points yielded by bivariate analyses to select the variable to be included in multivariate analysis is given.

  2. Observations and Models of Galaxy Assembly Bias

    NASA Astrophysics Data System (ADS)

    Campbell, Duncan A.

    2017-01-01

    The assembly history of dark matter haloes imparts various correlations between a halo’s physical properties and its large scale environment, i.e. assembly bias. It is common for models of the galaxy-halo connection to assume that galaxy properties are only a function of halo mass, implicitly ignoring how assembly bias may affect galaxies. Recently, programs to model and constrain the degree to which galaxy properties are influenced by assembly bias have been undertaken; however, the extent and character of galaxy assembly bias remains a mystery. Nevertheless, characterizing and modeling galaxy assembly bias is an important step in understanding galaxy evolution and limiting any systematic effects assembly bias may pose in cosmological measurements using galaxy surveys.I will present work on modeling and constraining the effect of assembly bias in two galaxy properties: stellar mass and star-formation rate. Conditional abundance matching allows for these galaxy properties to be tied to halo formation history to a variable degree, making studies of the relative strength of assembly bias possible. Galaxy-galaxy clustering and galactic conformity, the degree to which galaxy color is correlated between neighbors, are sensitive observational measures of galaxy assembly bias. I will show how these measurements can be used to constrain galaxy assembly bias and the peril of ignoring it.

  3. Selection bias in rheumatic disease research

    PubMed Central

    Choi, Hyon K.; Nguyen, Uyen-Sa; Niu, Jingbo; Danaei, Goodarz; Zhang, Yuqing

    2014-01-01

    The identification of modifiable risk factors for the development of rheumatic conditions and their sequelae is crucial for reducing the substantial worldwide burden of these diseases. However, the validity of such research can be threatened by sources of bias, including confounding, measurement and selection biases. In this Review, we discuss potentially major issues of selection bias—a type of bias frequently overshadowed by other bias and feasibility issues, despite being equally or more problematic—in key areas of rheumatic disease research. We present index event bias (a type of selection bias) as one of the potentially unifying reasons behind some unexpected findings, such as the ‘risk factor paradox’—a phenomenon exemplified by the discrepant effects of certain risk factors on the development versus the progression of osteoarthritis (OA) or rheumatoid arthritis (RA). We also discuss potential selection biases owing to differential loss to follow-up in RA and OA research, as well as those due to the depletion of susceptibles (prevalent user bias) and immortal time bias. The lesson remains that selection bias can be ubiquitous and, therefore, has the potential to lead the field astray. Thus, we conclude with suggestions to help investigators avoid such issues and limit the impact on future rheumatology research. PMID:24686510

  4. Trends in MODIS Geolocation Error Analysis

    NASA Technical Reports Server (NTRS)

    Wolfe, R. E.; Nishihama, Masahiro

    2009-01-01

    Data from the two MODIS instruments have been accurately geolocated (Earth located) to enable retrieval of global geophysical parameters. The authors describe the approach used to geolocate with sub-pixel accuracy over nine years of data from M0DIS on NASA's E0S Terra spacecraft and seven years of data from MODIS on the Aqua spacecraft. The approach uses a geometric model of the MODIS instruments, accurate navigation (orbit and attitude) data and an accurate Earth terrain model to compute the location of each MODIS pixel. The error analysis approach automatically matches MODIS imagery with a global set of over 1,000 ground control points from the finer-resolution Landsat satellite to measure static biases and trends in the MO0lS geometric model parameters. Both within orbit and yearly thermally induced cyclic variations in the pointing have been found as well as a general long-term trend.

  5. A meta-analysis of the effect of cognitive bias modification on anxiety and depression.

    PubMed

    Hallion, Lauren S; Ruscio, Ayelet Meron

    2011-11-01

    Cognitive biases have been theorized to play a critical role in the onset and maintenance of anxiety and depression. Cognitive bias modification (CBM), an experimental paradigm that uses training to induce maladaptive or adaptive cognitive biases, was developed to test these causal models. Although CBM has generated considerable interest in the past decade, both as an experimental paradigm and as a form of treatment, there have been no quantitative reviews of the effect of CBM on anxiety and depression. This meta-analysis of 45 studies (2,591 participants) assessed the effect of CBM on cognitive biases and on anxiety and depression. CBM had a medium effect on biases (g = 0.49) that was stronger for interpretation (g = 0.81) than for attention (g = 0.29) biases. CBM further had a small effect on anxiety and depression (g = 0.13), although this effect was reliable only when symptoms were assessed after participants experienced a stressor (g = 0.23). When anxiety and depression were examined separately, CBM significantly modified anxiety but not depression. There was a nonsignificant trend toward a larger effect for studies including multiple training sessions. These findings are broadly consistent with cognitive theories of anxiety and depression that propose an interactive effect of cognitive biases and stressors on these symptoms. However, the small effect sizes observed here suggest that this effect may be more modest than previously believed.

  6. Asymmetric divertor biasing in MAST

    NASA Astrophysics Data System (ADS)

    Helander, P.; Cohen, R.; Counsell, G. C.; Ryutov, D. D.

    2002-11-01

    Experiments are being carried out on the Mega-Ampere Spherical Tokamak (MAST) where the divertor tiles are electrically biased in a toroidally alternating way. The aim is to induce convective cells in the divertor plasma, broaden the SOL and reduce the divertor heat load. This paper describes the underlying theory and experimental results. Criteria are presented for achieving strong broadening and exciting shear-flow turbulence in the SOL, and properties of the expected turbulence are derived. It is also shown that magnetic shear near the X-point is likely to confine the potential perturbations to the divertor region, leaving the part of the SOL that is in direct contact with the core plasma intact. Preliminary comparison of the theory with MAST data is encouraging: the distortion of the heat deposition pattern, its broadening, and the incremental heat load are qualitatively in agreement; quantitative comparisons are underway.

  7. Social reward shapes attentional biases.

    PubMed

    Anderson, Brian A

    2016-01-01

    Paying attention to stimuli that predict a reward outcome is important for an organism to survive and thrive. When visual stimuli are associated with tangible, extrinsic rewards such as money or food, these stimuli acquire high attentional priority and come to automatically capture attention. In humans and other primates, however, many behaviors are not motivated directly by such extrinsic rewards, but rather by the social feedback that results from performing those behaviors. In the present study, I examine whether positive social feedback can similarly influence attentional bias. The results show that stimuli previously associated with a high probability of positive social feedback elicit value-driven attentional capture, much like stimuli associated with extrinsic rewards. Unlike with extrinsic rewards, however, such stimuli also influence task-specific motivation. My findings offer a potential mechanism by which social reward shapes the information that we prioritize when perceiving the world around us.

  8. Biased tracers and time evolution

    SciTech Connect

    Mirbabayi, Mehrdad; Zaldarriaga, Matias; Schmidt, Fabian E-mail: fabians@mpa-garching.mpg.de

    2015-07-01

    We study the effect of time evolution on galaxy bias. We argue that at any order in perturbations, the galaxy density contrast can be expressed in terms of a finite set of locally measurable operators made of spatial and temporal derivatives of the Newtonian potential. This is checked in an explicit third order calculation. There is a systematic way to derive a basis for these operators. This basis spans a larger space than the expansion in gravitational and velocity potentials usually employed, although new operators only appear at fourth order. The basis is argued to be closed under renormalization. Most of the arguments also apply to the structure of the counter-terms in the effective theory of large-scale structure.

  9. Reexamining our bias against heuristics.

    PubMed

    McLaughlin, Kevin; Eva, Kevin W; Norman, Geoff R

    2014-08-01

    Using heuristics offers several cognitive advantages, such as increased speed and reduced effort when making decisions, in addition to allowing us to make decision in situations where missing data do not allow for formal reasoning. But the traditional view of heuristics is that they trade accuracy for efficiency. Here the authors discuss sources of bias in the literature implicating the use of heuristics in diagnostic error and highlight the fact that there are also data suggesting that under certain circumstances using heuristics may lead to better decisions that formal analysis. They suggest that diagnostic error is frequently misattributed to the use of heuristics and propose an alternative view whereby content knowledge is the root cause of diagnostic performance and heuristics lie on the causal pathway between knowledge and diagnostic error or success.

  10. Understanding bias in provenance studies

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Andò, Sergio; Malusà, Marco; Vezzoli, Giovanni

    2010-05-01

    Innumerable pieces of information are stored in the sedimentary archive. Each single sediment layer contains billions of detrital grains, and every grain preserves imprints of its geological story. If we learn to read, compare, and combine these messages properly, through a deeper understanding of physical and chemical processes that modify sediment composition during the sedimentary cycle, provenance analysis may eventually enable us to reconstruct more accurately the geological processes that shaped the Earth's crust in the past. Interpreting detrital modes is not straightforward because provenance signals issued from source rocks become progressively blurred by multiple noises in the sedimentary environment ("environmental bias"; Komar, 2007), and finally during post-depositional history ("diagenetic bias"; Morton and Hallsworth, 2007). During transport and deposition, detrital minerals are segregated in different size fractions and environments according to their size, density and shape (Rubey, 1933; Garzanti et al., 2008). Heavy-mineral concentration can increase by an order of magnitude due to selective-entrainment effects, with potentially overwhelming impact on chemical composition and provenance estimates based on detrital-geochronology data (Garzanti et al., 2009). Conversely, heavy-mineral concentration is typically reduced by an order of magnitude in Alpine and Himalayan foreland-basin deposits older than the Pleistocene (Garzanti and Andò, 2007). Extensive chemical dissolution can occur even prior to deposition during weathering in hot humid climates (Velbel, 2007). Primary provenance signals can be isolated and assessed by studying first modern sediments in hyperarid settings (i.e., free from diagenetic and weathering bias). Next, weathering, hydraulic-sorting, and diagenetic effects can be singled out by analysing sediments of similar provenance produced in contrasting climatic conditions, sediments transported in diverse modes and deposited in

  11. [Recent demographic trends].

    PubMed

    1984-01-01

    A review of demographic trends in Luxembourg in 1983 is presented. The most significant trend was a decline in the number of marriages to the lowest level since World War II. Topics covered include fertility, nuptiality and divorce, mortality, natural increase, migration, and adoptions. Selected vital statistics for the first six months of 1984 are also presented.

  12. Some Current Population Trends.

    ERIC Educational Resources Information Center

    Taeuber, Conrad

    Population trends in the 1960's and early 1970's are examined in this 1972 speech in terms of overall national trends, the growth of metropolitan areas, the rural population, geographic shifts, internal migration, the black population, and living arrangements. It is noted that population growth in the 1960's was unevenly distributed within age…

  13. Trends in methodological differences

    Treesearch

    Daniel J. Stynes; Malcolm I. Bevins; Tommy L. Brown

    1980-01-01

    Inconsistency in data collection has confounded attempts to identify and forecast outdoor recreation trends. Problems are highlighted through an evaluation of the methods employed in national outdoor recreation participation surveys and projections. Recommendations are advanced for improving data collection, trend measurement, and forecasting within outdoor recreation...

  14. General Achievement Trends: Colorado

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  15. General Achievement Trends: Nevada

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  16. Trends Shaping Education 2010

    ERIC Educational Resources Information Center

    OECD Publishing (NJ3), 2010

    2010-01-01

    "Trends Shaping Education 2010" brings together evidence showing the effects on education of globalisation, social challenges, changes in the workplace, the transformation of childhood, and ICT. To make the content accessible, each trend is presented on a double page, containing an introduction, two charts with brief descriptive text and a set of…

  17. Trends Shaping Education 2010

    ERIC Educational Resources Information Center

    OECD Publishing (NJ3), 2010

    2010-01-01

    "Trends Shaping Education 2010" brings together evidence showing the effects on education of globalisation, social challenges, changes in the workplace, the transformation of childhood, and ICT. To make the content accessible, each trend is presented on a double page, containing an introduction, two charts with brief descriptive text and a set of…

  18. Trends in Educational Technology.

    ERIC Educational Resources Information Center

    Ely, Donald P.

    Based on the findings of a content analysis of representative literature on educational technology, this report examines the trends in educational technology from October 1, 1990 through September 30, 1991. Ten trends for 1991 are identified and discussed: (1) the creation of technology-based teaching/learning products is based largely on…

  19. TRENDS IN ADULT READING.

    ERIC Educational Resources Information Center

    MILLER, JUSTIN H.

    TRENDS EVIDENT IN ADULT READING DURING THE 1960'S IN THE AREAS OF ADMINISTRATION, PROGRAMS, TEACHING, TECHNIQUES, RESEARCH PROJECTS, AND METHODS OF PROMOTION OF READING PROGRAMS ARE DISCUSSED. TWO INSTANCES OF COMMERCIAL EXPLOITATION BASED ON INTENSE AND OFTEN FALLACIOUS ADVERTISING AND ON PUBLIC IGNORANCE ARE CITED. A POSITIVE TREND IN THE AREA…

  20. Symmetry as Bias: Rediscovering Special Relativity

    NASA Technical Reports Server (NTRS)

    Lowry, Michael R.

    1992-01-01

    This paper describes a rational reconstruction of Einstein's discovery of special relativity, validated through an implementation: the Erlanger program. Einstein's discovery of special relativity revolutionized both the content of physics and the research strategy used by theoretical physicists. This research strategy entails a mutual bootstrapping process between a hypothesis space for biases, defined through different postulated symmetries of the universe, and a hypothesis space for physical theories. The invariance principle mutually constrains these two spaces. The invariance principle enables detecting when an evolving physical theory becomes inconsistent with its bias, and also when the biases for theories describing different phenomena are inconsistent. Structural properties of the invariance principle facilitate generating a new bias when an inconsistency is detected. After a new bias is generated. this principle facilitates reformulating the old, inconsistent theory by treating the latter as a limiting approximation. The structural properties of the invariance principle can be suitably generalized to other types of biases to enable primal-dual learning.

  1. Publication Bias in Methodological Computational Research

    PubMed Central

    Boulesteix, Anne-Laure; Stierle, Veronika; Hapfelmeier, Alexander

    2015-01-01

    The problem of publication bias has long been discussed in research fields such as medicine. There is a consensus that publication bias is a reality and that solutions should be found to reduce it. In methodological computational research, including cancer informatics, publication bias may also be at work. The publication of negative research findings is certainly also a relevant issue, but has attracted very little attention to date. The present paper aims at providing a new formal framework to describe the notion of publication bias in the context of methodological computational research, facilitate and stimulate discussions on this topic, and increase awareness in the scientific community. We report an exemplary pilot study that aims at gaining experiences with the collection and analysis of information on unpublished research efforts with respect to publication bias, and we outline the encountered problems. Based on these experiences, we try to formalize the notion of publication bias. PMID:26508827

  2. Is probabilistic bias analysis approximately Bayesian?

    PubMed Central

    MacLehose, Richard F.; Gustafson, Paul

    2011-01-01

    Case-control studies are particularly susceptible to differential exposure misclassification when exposure status is determined following incident case status. Probabilistic bias analysis methods have been developed as ways to adjust standard effect estimates based on the sensitivity and specificity of exposure misclassification. The iterative sampling method advocated in probabilistic bias analysis bears a distinct resemblance to a Bayesian adjustment; however, it is not identical. Furthermore, without a formal theoretical framework (Bayesian or frequentist), the results of a probabilistic bias analysis remain somewhat difficult to interpret. We describe, both theoretically and empirically, the extent to which probabilistic bias analysis can be viewed as approximately Bayesian. While the differences between probabilistic bias analysis and Bayesian approaches to misclassification can be substantial, these situations often involve unrealistic prior specifications and are relatively easy to detect. Outside of these special cases, probabilistic bias analysis and Bayesian approaches to exposure misclassification in case-control studies appear to perform equally well. PMID:22157311

  3. Professional Culture and Climate: Addressing Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Knezek, Patricia

    2016-10-01

    Unconscious bias reflects expectations or stereotypes that influence our judgments of others (regardless of our own group). Everyone has unconscious biases. The end result of unconscious bias can be an accumulation of advantage or disadvantage that impacts the long term career success of individuals, depending on which biases they are subject to. In order to foster a professional culture and climate, being aware of these unconscious biases and mitigating against them is a first step. This is particularly important when judgements are needed, such as in cases for recruitment, choice of speakers for conferences, and even reviewing papers submitted for publication. This presentation will cover how unconscious bias manifests itself, what evidence exists to demonstrate it exists, and ways it can be addressed.

  4. On evolutionary explanations of cognitive biases.

    PubMed

    Marshall, James A R; Trimmer, Pete C; Houston, Alasdair I; McNamara, John M

    2013-08-01

    Apparently irrational biases such as overconfidence, optimism, and pessimism are increasingly studied by biologists, psychologists, and neuroscientists. Functional explanations of such phenomena are essential; we argue that recent proposals, focused on benefits from overestimating the probability of success in conflicts or practising self-deception to better deceive others, are still lacking in crucial regards. Attention must be paid to the difference between cognitive and outcome biases; outcome biases are suboptimal, yet cognitive biases can be optimal. However, given that cognitive biases are subjectively experienced by affected individuals, developing theory and collecting evidence on them poses challenges. An evolutionary theory of cognitive bias might require closer integration of function and mechanism, analysing the evolution of constraints imposed by the mechanisms that determine behaviour.

  5. Cognitive Biases and Nonverbal Cue Availability in Detecting Deception

    ERIC Educational Resources Information Center

    Burgoon, Judee K.; Blair, J. Pete; Strom, Renee E.

    2008-01-01

    In potentially deceptive situations, people rely on mental shortcuts to help process information. These heuristic judgments are often biased and result in inaccurate assessments of sender veracity. Four such biases--truth bias, visual bias, demeanor bias, and expectancy violation bias--were examined in a judgment experiment that varied nonverbal…

  6. When Do Children Exhibit a "Yes" Bias?

    ERIC Educational Resources Information Center

    Okanda, Mako; Itakura, Shoji

    2010-01-01

    This study investigated whether one hundred and thirty-five 3- to 6-year-old children exhibit a yes bias to various yes-no questions and whether their knowledge status affects the production of a yes bias. Three-year-olds exhibited a yes bias to all yes-no questions such as "preference-object" and "knowledge-object" questions pertaining to…

  7. When Do Children Exhibit a "Yes" Bias?

    ERIC Educational Resources Information Center

    Okanda, Mako; Itakura, Shoji

    2010-01-01

    This study investigated whether one hundred and thirty-five 3- to 6-year-old children exhibit a yes bias to various yes-no questions and whether their knowledge status affects the production of a yes bias. Three-year-olds exhibited a yes bias to all yes-no questions such as "preference-object" and "knowledge-object" questions pertaining to…

  8. Electric control of exchange bias training.

    PubMed

    Echtenkamp, W; Binek, Ch

    2013-11-01

    Voltage-controlled exchange bias training and tunability are introduced. Isothermal voltage pulses are used to reverse the antiferromagnetic order parameter of magnetoelectric Cr(2)O(3), and thus continuously tune the exchange bias of an adjacent CoPd film. Voltage-controlled exchange bias training is initialized by tuning the antiferromagnetic interface into a nonequilibrium state incommensurate with the underlying bulk. Interpretation of these hitherto unreported effects contributes to new understanding in electrically controlled magnetism.

  9. Electric Control of Exchange Bias Training

    NASA Astrophysics Data System (ADS)

    Echtenkamp, W.; Binek, Ch.

    2013-11-01

    Voltage-controlled exchange bias training and tunability are introduced. Isothermal voltage pulses are used to reverse the antiferromagnetic order parameter of magnetoelectric Cr2O3, and thus continuously tune the exchange bias of an adjacent CoPd film. Voltage-controlled exchange bias training is initialized by tuning the antiferromagnetic interface into a nonequilibrium state incommensurate with the underlying bulk. Interpretation of these hitherto unreported effects contributes to new understanding in electrically controlled magnetism.

  10. The truth and bias model of judgment.

    PubMed

    West, Tessa V; Kenny, David A

    2011-04-01

    We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of the attraction and the value is the location toward which the judgment is attracted. The model also makes a formal theoretical distinction between bias and moderator variables. Two major classes of biases are discussed: biases that are measured with variables (e.g., assumed similarity) and directional bias, which refers to the extent to which judgments are pulled toward 1 end of the judgment continuum. Moderator variables are conceptualized as variables that affect the accuracy and bias forces but that do not affect judgments directly. We illustrate the model with 4 examples. We discuss the theoretical, empirical, methodological, measurement, and design implications of the model. 2011 APA, all rights reserved

  11. Identifying and Avoiding Bias in Research

    PubMed Central

    Pannucci, Christopher J.; Wilkins, Edwin G.

    2010-01-01

    This narrative review provides an overview on the topic of bias as part of Plastic and Reconstructive Surgery's series of articles on evidence-based medicine. Bias can occur in the planning, data collection, analysis, and publication phases of research. Understanding research bias allows readers to critically and independently review the scientific literature and avoid treatments which are suboptimal or potentially harmful. A thorough understanding of bias and how it affects study results is essential for the practice of evidence-based medicine. PMID:20679844

  12. Detecting Gender Bias Through Test Item Analysis

    NASA Astrophysics Data System (ADS)

    González-Espada, Wilson J.

    2009-03-01

    Many physical science and physics instructors might not be trained in pedagogically appropriate test construction methods. This could lead to test items that do not measure what they are intended to measure. A subgroup of these items might show bias against some groups of students. This paper describes how the author became aware of potentially biased items against females in his examinations, which led to the exploration of fundamental issues related to item validity, gender bias, and differential item functioning, or DIF. A brief discussion of DIF in the context of university courses, as well as practical suggestions to detect possible gender-biased items, follows.

  13. Adaptable history biases in human perceptual decisions

    PubMed Central

    Abrahamyan, Arman; Silva, Laura Luz; Dakin, Steven C.; Gardner, Justin L.

    2016-01-01

    When making choices under conditions of perceptual uncertainty, past experience can play a vital role. However, it can also lead to biases that worsen decisions. Consistent with previous observations, we found that human choices are influenced by the success or failure of past choices even in a standard two-alternative detection task, where choice history is irrelevant. The typical bias was one that made the subject switch choices after a failure. These choice history biases led to poorer performance and were similar for observers in different countries. They were well captured by a simple logistic regression model that had been previously applied to describe psychophysical performance in mice. Such irrational biases seem at odds with the principles of reinforcement learning, which would predict exquisite adaptability to choice history. We therefore asked whether subjects could adapt their irrational biases following changes in trial order statistics. Adaptability was strong in the direction that confirmed a subject’s default biases, but weaker in the opposite direction, so that existing biases could not be eradicated. We conclude that humans can adapt choice history biases, but cannot easily overcome existing biases even if irrational in the current context: adaptation is more sensitive to confirmatory than contradictory statistics. PMID:27330086

  14. Chronic and acute biases in perceptual stabilization

    PubMed Central

    Al-Dossari, Munira; Blake, Randolph; Brascamp, Jan W.; Freeman, Alan W.

    2015-01-01

    When perceptually ambiguous stimuli are presented intermittently, the percept on one presentation tends to be the same as that on the previous presentation. The role of short-term, acute biases in the production of this perceptual stability is relatively well understood. In addition, however, long-lasting, chronic bias may also contribute to stability. In this paper we develop indices for both biases and for stability, and show that stability can be expressed as a sum of contributions from the two types of bias. We then apply this analytical procedure to binocular rivalry, showing that adjustment of the monocular contrasts can alter the relative contributions of the two biases. Stability is mainly determined by chronic bias when the contrasts are equal, but acute bias dominates stability when right-eye contrast is set lower than left-eye contrast. Finally, we show that the right-eye bias persists in continuous binocular rivalry. Our findings reveal a previously unappreciated contribution of chronic bias to stable perception. PMID:26641947

  15. Bayesian long branch attraction bias and corrections.

    PubMed

    Susko, Edward

    2015-03-01

    Previous work on the star-tree paradox has shown that Bayesian methods suffer from a long branch attraction bias. That work is extended to settings involving more taxa and partially resolved trees. The long branch attraction bias is confirmed to arise more broadly and an additional source of bias is found. A by-product of the analysis is methods that correct for biases toward particular topologies. The corrections can be easily calculated using existing Bayesian software. Posterior support for a set of two or more trees can thus be supplemented with corrected versions to cross-check or replace results. Simulations show the corrections to be highly effective.

  16. Biases in the production and reception of collective knowledge: the case of hindsight bias in Wikipedia.

    PubMed

    Oeberst, Aileen; von der Beck, Ina; D Back, Mitja; Cress, Ulrike; Nestler, Steffen

    2017-04-17

    The Web 2.0 enabled collaboration at an unprecedented level. In one of the flagships of mass collaboration-Wikipedia-a large number of authors socially negotiate the world's largest compendium of knowledge. Several guidelines in Wikipedia restrict contributions to verifiable information from reliable sources to ensure recognized knowledge. Much psychological research demonstrates, however, that individual information processing is biased. This poses the question whether individual biases translate to Wikipedia articles or whether they are prevented by its guidelines. The present research makes use of hindsight bias to examine this question. To this end, we analyzed foresight and hindsight versions of Wikipedia articles regarding a broad variety of events (Study 1). We found the majority of articles not to contain traces of hindsight bias-contrary to prior individual research. However, for a particular category of events-disasters-we found robust evidence for hindsight bias. In a lab experiment (Study 2), we then examined whether individuals' hindsight bias is translated into articles under controlled conditions and tested whether collaborative writing-as present in Wikipedia-affects the resultant bias (vs. individual writing). Finally, we investigated the impact of biased Wikipedia articles on readers (Study 3). As predicted, biased articles elicited a hindsight bias in readers, who had not known of the event previously. Moreover, biased articles also affected individuals who knew about the event already, and who had already developed a hindsight bias: biased articles further increased their hindsight.

  17. The Contribution of Atmospheric Circulation and Coverage Bias to the Warming Hiatus

    NASA Astrophysics Data System (ADS)

    Saffioti, Claudio; Fischer, Erich M.; Knutti, Reto

    2015-04-01

    The global warming trend appears to have slackened or even halted since about 1998, in clear contrast with the strong warming signal projected by the CMIP5 multi-model mean for recent years. This warming hiatus shows a strong seasonal and geographical asymmetry, with cooling in the Northern Hemisphere winter, especially over land, and warming elsewhere and in the other seasons. Many factors have been suggested to contribute to the warming hiatus, including changes in solar radiative forcing, tropospheric and stratospheric aerosols, internal variability in the Atlantic and the Equatorial Pacific, wind stress variability or a combination of those. In addition, deficiencies due to the incomplete observational coverage have led to an underestimation of recent temperature trends. Although the above factors can account for the reduced warming trends, it is not clear whether they can also explain the spatial and temporal characteristics of the current slow-down in the rate of global warming. Working on five different reanalyses and on the HadCRUT4 temperature records, we quantify how internal atmospheric variability in the extratropical Northern Hemisphere (20-90°N) contributed to the spatial and seasonal asymmetry of the hiatus in the period 1998-2012 and how temperature trends were impacted by the incomplete observational coverage. In order to determine the circulation-induced contribution to temperature trends we apply a dynamical adjustment technique by sampling atmospheric variability through empirical orthogonal functions. We further test how missing observations influenced the observed warming by introducing the HadCRUT4 coverage bias in reanalysis temperatures. We find that the temperature trends in 1998-2012 can be reconciled with the long-term trends in the period 1960-2012 when accounting for the effects of natural variability and coverage bias. The contributions of atmospheric dynamics and incomplete coverage to the Northern Hemispheric and global DJF trends

  18. Geographic Information System mapping as a tool to assess nonresponse bias in survey research.

    PubMed

    Hansen, Richard A; Henley, Amanda Clarke; Brouwer, Emily S; Oraefo, Adaora N; Roth, Mary T

    2007-09-01

    Surveys are a useful tool for assessing professional practice patterns, although declining response rates have caused concern over external validity. This is particularly relevant to Web-based surveys, where response rates traditionally have been lower than with paper mail surveys. In a 2005 survey of North Carolina community pharmacy managers using a Web-based data collection instrument, we achieved an overall response rate of 23%. To explore nonresponse bias using accepted methods and to test whether Geographic Information System mapping is a useful tool for assessing response bias. Cross-sectional survey of 1593 community pharmacy managers in North Carolina using a Web-based tool. Nonresponse bias was assessed quantitatively by comparing early responders with late responders (ie, wave analysis) and by comparing respondents with nonrespondents with regard to known pharmacy, pharmacist, and population characteristics. Significant variables from these analyses were then mapped using ArcGIS 9.1. Pharmacy type was identified as a predictor of response, with independent pharmacies less likely to respond than chain pharmacies (odds ratio 0.75; 95% confidence interval 0.59-0.95). This conclusion was consistent in the wave analysis and the analysis of known population characteristics. Other county-level variables such as the number of physicians per capita, income, and the percentage of residents eligible for Medicaid showed trends but were not statistically significant (P<.1). Geographic Information System mapping was able to descriptively illustrate nonresponse bias for pharmacy type but trends were more difficult to detect for statistically insignificant trends. The best way to avoid nonresponse bias is to improve response rates. When this is not possible, Geographic Information System mapping has some utility for assessing nonresponse bias, and for aggregating known population characteristics based on location. It is most useful in conjunction with other accepted

  19. Bias correction of global and regional simulated daily precipitation and surface mean temperature over Southeast Asia using quantile mapping method

    NASA Astrophysics Data System (ADS)

    Ngai, Sheau Tieh; Tangang, Fredolin; Juneng, Liew

    2017-02-01

    A trend preserving quantile mapping (QM) method was applied to adjust the biases of the global and regional climate models (GCM and RCMs) simulated daily precipitation and surface mean temperature over Southeast Asia regions based on APHRODITE dataset. Output from four different RCMs as well as their driving GCM in CORDEX-EA archive were corrected to examine the added value of RCMs dynamical downscaling in the context of bias adjustment. The result shows that the RCM biases are comparable to that of the GCM biases. In some instances, RCMs amplified the GCM biases. Generally, QM method substantially improves the biases for both precipitation and temperature. However, the bias adjustment method works better for surface mean temperature and less so for daily precipitation. The large inter-models variability is reduced remarkably after bias adjustment. Overall, study indicates no strong evident that RCMs downscaling as an immediate step before bias correction provides additional improvement to the sub-regional climate compared to the correction directly carried out on their forcing GCM.

  20. Attentional control predicts change in bias in response to attentional bias modification.

    PubMed

    Basanovic, Julian; Notebaert, Lies; Grafton, Ben; Hirsch, Colette R; Clarke, Patrick J F

    2017-09-11

    Procedures that effectively modify attentional bias to negative information have been examined for their potential to be a source of therapeutic change in emotional vulnerability. However, the degree to which these procedures modify attentional bias is subject to individual differences. This generates the need to understand the mechanisms that influence attentional bias change across individuals. The present study investigated the association between individual differences in attentional control and individual differences in the magnitude of bias change evoked by an attentional bias modification procedure. The findings demonstrate that individual differences in two facets of attentional control, control of attentional inhibition and control of attentional selectivity, were positively associated with individual differences in the magnitude of attentional bias change. The present findings inform upon the cognitive mechanisms underpinning change in attentional bias, and identify a target cognitive process for research seeking to enhance the therapeutic effectiveness of attentional bias modification procedures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. An assessment of change in risk perception and optimistic bias for hurricanes among Gulf Coast residents.

    PubMed

    Trumbo, Craig; Meyer, Michelle A; Marlatt, Holly; Peek, Lori; Morrissey, Bridget

    2014-06-01

    This study focuses on levels of concern for hurricanes among individuals living along the Gulf Coast during the quiescent two-year period following the exceptionally destructive 2005 hurricane season. A small study of risk perception and optimistic bias was conducted immediately following Hurricanes Katrina and Rita. Two years later, a follow-up was done in which respondents were recontacted. This provided an opportunity to examine changes, and potential causal ordering, in risk perception and optimistic bias. The analysis uses 201 panel respondents who were matched across the two mail surveys. Measures included hurricane risk perception, optimistic bias for hurricane evacuation, past hurricane experience, and a small set of demographic variables (age, sex, income, and education). Paired t-tests were used to compare scores across time. Hurricane risk perception declined and optimistic bias increased. Cross-lagged correlations were used to test the potential causal ordering between risk perception and optimistic bias, with a weak effect suggesting the former affects the latter. Additional cross-lagged analysis using structural equation modeling was used to look more closely at the components of optimistic bias (risk to self vs. risk to others). A significant and stronger potentially causal effect from risk perception to optimistic bias was found. Analysis of the experience and demographic variables' effects on risk perception and optimistic bias, and their change, provided mixed results. The lessening of risk perception and increase in optimistic bias over the period of quiescence suggest that risk communicators and emergency managers should direct attention toward reversing these trends to increase disaster preparedness.

  2. Mutation Bias is the Driving Force of Codon Usage in the Gallus gallus genome

    PubMed Central

    Rao, Yousheng; Wu, Guozuo; Wang, Zhangfeng; Chai, Xuewen; Nie, Qinghua; Zhang, Xiquan

    2011-01-01

    Synonymous codons are used with different frequencies both among species and among genes within the same genome and are controlled by neutral processes (such as mutation and drift) as well as by selection. Up to now, a systematic examination of the codon usage for the chicken genome has not been performed. Here, we carried out a whole genome analysis of the chicken genome by the use of the relative synonymous codon usage (RSCU) method and identified 11 putative optimal codons, all of them ending with uracil (U), which is significantly departing from the pattern observed in other eukaryotes. Optimal codons in the chicken genome are most likely the ones corresponding to highly expressed transfer RNA (tRNAs) or tRNA gene copy numbers in the cell. Codon bias, measured as the frequency of optimal codons (Fop), is negatively correlated with the G + C content, recombination rate, but positively correlated with gene expression, protein length, gene length and intron length. The positive correlation between codon bias and protein, gene and intron length is quite different from other multi-cellular organism, as this trend has been only found in unicellular organisms. Our data displayed that regional G + C content explains a large proportion of the variance of codon bias in chicken. Stepwise selection model analyses indicate that G + C content of coding sequence is the most important factor for codon bias. It appears that variation in the G + C content of CDSs accounts for over 60% of the variation of codon bias. This study suggests that both mutation bias and selection contribute to codon bias. However, mutation bias is the driving force of the codon usage in the Gallus gallus genome. Our data also provide evidence that the negative correlation between codon bias and recombination rates in G. gallus is determined mostly by recombination-dependent mutational patterns. PMID:22039174

  3. Modeling confirmation bias and polarization

    PubMed Central

    Del Vicario, Michela; Scala, Antonio; Caldarelli, Guido; Stanley, H. Eugene; Quattrociocchi, Walter

    2017-01-01

    Online users tend to select claims that adhere to their system of beliefs and to ignore dissenting information. Confirmation bias, indeed, plays a pivotal role in viral phenomena. Furthermore, the wide availability of content on the web fosters the aggregation of likeminded people where debates tend to enforce group polarization. Such a configuration might alter the public debate and thus the formation of the public opinion. In this paper we provide a mathematical model to study online social debates and the related polarization dynamics. We assume the basic updating rule of the Bounded Confidence Model (BCM) and we develop two variations a) the Rewire with Bounded Confidence Model (RBCM), in which discordant links are broken until convergence is reached; and b) the Unbounded Confidence Model, under which the interaction among discordant pairs of users is allowed even with a negative feedback, either with the rewiring step (RUCM) or without it (UCM). From numerical simulations we find that the new models (UCM and RUCM), unlike the BCM, are able to explain the coexistence of two stable final opinions, often observed in reality. Lastly, we present a mean field approximation of the newly introduced models. PMID:28074874

  4. Haploinsufficiency predictions without study bias

    PubMed Central

    Steinberg, Julia; Honti, Frantisek; Meader, Stephen; Webber, Caleb

    2015-01-01

    Any given human individual carries multiple genetic variants that disrupt protein-coding genes, through structural variation, as well as nucleotide variants and indels. Predicting the phenotypic consequences of a gene disruption remains a significant challenge. Current approaches employ information from a range of biological networks to predict which human genes are haploinsufficient (meaning two copies are required for normal function) or essential (meaning at least one copy is required for viability). Using recently available study gene sets, we show that these approaches are strongly biased towards providing accurate predictions for well-studied genes. By contrast, we derive a haploinsufficiency score from a combination of unbiased large-scale high-throughput datasets, including gene co-expression and genetic variation in over 6000 human exomes. Our approach provides a haploinsufficiency prediction for over twice as many genes currently unassociated with papers listed in Pubmed as three commonly-used approaches, and outperforms these approaches for predicting haploinsufficiency for less-studied genes. We also show that fine-tuning the predictor on a set of well-studied ‘gold standard’ haploinsufficient genes does not improve the prediction for less-studied genes. This new score can readily be used to prioritize gene disruptions resulting from any genetic variant, including copy number variants, indels and single-nucleotide variants. PMID:26001969

  5. Modeling confirmation bias and polarization

    NASA Astrophysics Data System (ADS)

    Del Vicario, Michela; Scala, Antonio; Caldarelli, Guido; Stanley, H. Eugene; Quattrociocchi, Walter

    2017-01-01

    Online users tend to select claims that adhere to their system of beliefs and to ignore dissenting information. Confirmation bias, indeed, plays a pivotal role in viral phenomena. Furthermore, the wide availability of content on the web fosters the aggregation of likeminded people where debates tend to enforce group polarization. Such a configuration might alter the public debate and thus the formation of the public opinion. In this paper we provide a mathematical model to study online social debates and the related polarization dynamics. We assume the basic updating rule of the Bounded Confidence Model (BCM) and we develop two variations a) the Rewire with Bounded Confidence Model (RBCM), in which discordant links are broken until convergence is reached; and b) the Unbounded Confidence Model, under which the interaction among discordant pairs of users is allowed even with a negative feedback, either with the rewiring step (RUCM) or without it (UCM). From numerical simulations we find that the new models (UCM and RUCM), unlike the BCM, are able to explain the coexistence of two stable final opinions, often observed in reality. Lastly, we present a mean field approximation of the newly introduced models.

  6. Codon usage in Caenorhabditis elegans: delineation of translational selection and mutational biases.

    PubMed Central

    Stenico, M; Lloyd, A T; Sharp, P M

    1994-01-01

    Synonymous codon usage varies considerably among Caenorhabditis elegans genes. Multivariate statistical analyses reveal a single major trend among genes. At one end of the trend lie genes with relatively unbiased codon usage. These genes appear to be lowly expressed, and their patterns of codon usage are consistent with mutational biases influenced by the neighbouring nucleotide. At the other extreme lie genes with extremely biased codon usage. These genes appear to be highly expressed, and their codon usage seems to have been shaped by selection favouring a limited number of translationally optimal codons. Thus, the frequency of these optimal codons in a gene appears to be correlated with the level of gene expression, and may be a useful indicator in the case of genes (or open reading frames) whose expression levels (or even function) are unknown. A second, relatively minor trend among genes is correlated with the frequency of G at synonymously variable sites. It is not yet clear whether this trend reflects variation in base composition (or mutational biases) among regions of the C.elegans genome, or some other factor. Sequence divergence between C.elegans and C.briggsae has also been studied. PMID:8041603

  7. [Population trends in Luxembourg].

    PubMed

    1989-01-01

    Population trends in Luxembourg in 1988 are reviewed. Separate consideration is given to fertility, nuptiality and divorce, mortality, natural increase and migration, adoption, age and sex structure, and spatial distribution. Data are provided separately for the foreign resident population.

  8. [Recent demographic trends].

    PubMed

    1988-01-01

    Population trends in Luxembourg in 1987 are reviewed. Separate consideration is given to fertility, nuptiality and divorce, mortality, natural increase and migration, adoption, and family policy. Comparisons are made with the situation in other European countries.

  9. Breast Cancer Trends

    MedlinePlus

    ... Breast Cancer Funding: Young Breast Cancer Survivors Funding: Breast Cancer Genomics Statistics Rates by Race and Ethnicity Rates by State Risk by Age Trends What CDC Is Doing Research African American Women and Mass Media Campaign Public Service Announcements Print ...

  10. Bomber design trends

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.

    1986-01-01

    Some basic trends in bomber aircraft are traced from the pre-World War I era to the present time. The historic review includes bombers of many countries. The primary discussion, however, will be based on U.S. bomber programs and, to the extent possible, on USSR bomber programs. The bomber aircraft will be examined in terms of performance and mission capability.Characteristics will include power or thrust loading, wing loading, maximum speed, cruising speed, weight and weight distribution, and payload. These trends can be used to indicate the rationale for certain design types. Performance characteristics can be used to indicate potential mission objectives. The overall design trends should be useful in revealing the influence of mission objectives, the influence of advanced technology and, in turn, may be useful in predicting likely future trends.

  11. Trends in stratospheric temperature

    NASA Technical Reports Server (NTRS)

    Schoeberl, M. R.; Newman, P. A.; Rosenfield, J. E.; Angell, J.; Barnett, J.; Boville, B. A.; Chandra, S.; Fels, S.; Fleming, E.; Gelman, M.

    1989-01-01

    Stratospheric temperatures for long-term and recent trends and the determination of whether observed changes in upper stratospheric temperatures are consistent with observed ozone changes are discussed. The long-term temperature trends were determined up to 30mb from radiosonde analysis (since 1970) and rocketsondes (since 1969 and 1973) up to the lower mesosphere, principally in the Northern Hemisphere. The more recent trends (since 1979) incorporate satellite observations. The mechanisms that can produce recent temperature trends in the stratosphere are discussed. The following general effects are discussed: changes in ozone, changes in other radiatively active trace gases, changes in aerosols, changes in solar flux, and dynamical changes. Computations were made to estimate the temperature changes associated with the upper stratospheric ozone changes reported by the Solar Backscatter Ultraviolet (SBUV) instrument aboard Nimbus-7 and the Stratospheric Aerosol and Gas Experiment (SAGE) instruments.

  12. Fertilizer trends 1982

    SciTech Connect

    Bridges, J.D.

    1983-01-01

    Contents of this publication are as follows: TVA fertilizer program; the fertilizer market; trends in nutrient use; nitrogen; phosphate; potash; sulfur; Canada; North American production capacity data; and statistical sources and suggested references.

  13. Trends in mass murder.

    PubMed

    Lester, David

    2002-06-01

    From 1976 to 1996, the proportion of murder incidents with 5 or more victims showed no linear trend or association with selected social indicators, e.g., birth rate, unemployment rate, and homicide rate.

  14. Ozone Trend Detectability

    NASA Technical Reports Server (NTRS)

    Campbell, J. W. (Editor)

    1981-01-01

    The detection of anthropogenic disturbances in the Earth's ozone layer was studied. Two topics were addressed: (1) the level at which a trend in total ozoning is detected by existing data sources; and (2) empirical evidence in the prediction of the depletion in total ozone. Error sources are identified. The predictability of climatological series, whether empirical models can be trusted, and how errors in the Dobson total ozone data impact trend detectability, are discussed.

  15. Understanding Implicit Bias: What Educators Should Know

    ERIC Educational Resources Information Center

    Staats, Cheryl

    2016-01-01

    The desire to ensure the best for children is precisely why educators should become aware of the concept of implicit bias: the attitudes or stereotypes that affect our understanding, actions, and decisions in an unconscious manner. Operating outside of our conscious awareness, implicit biases are pervasive, and they can challenge even the most…

  16. Distractors--Can They Be Biased Too?

    ERIC Educational Resources Information Center

    Alagumalai, Sivakumar; Keeves, John P.

    1999-01-01

    How distractors in a test item function differentially is discussed. Also discussed are methods to identify distractor bias, including the Pearson chi square, likelihood-ratio chi square, and the Neyman weighted-least squares chi square tests. Problems from a physics test illustrate possible causes of distractor bias. (SLD)

  17. Understanding Unconscious Bias and Unintentional Racism

    ERIC Educational Resources Information Center

    Moule, Jean

    2009-01-01

    Unconscious biases affect one's relationships, whether they are fleeting relationships in airports or longer term relationships between teachers and students, teachers and parents, teachers and other educators. In this article, the author argues that understanding one's possible biases is essential for developing community in schools.…

  18. Hindsight Bias and Developing Theories of Mind

    ERIC Educational Resources Information Center

    Bernstein, Daniel M.; Atance, Cristina; Meltzoff, Andrew N.; Loftus, Geoffrey R.

    2007-01-01

    Although "hindsight bias" (the "I knew it all along" phenomenon) has been documented in adults, its development has not been investigated. This is despite the fact that hindsight bias errors closely resemble the errors children make on theory of mind (ToM) tasks. Two main goals of the present work were to (a) create a battery of hindsight tasks…

  19. The Battle over Studies of Faculty Bias

    ERIC Educational Resources Information Center

    Gravois, John

    2007-01-01

    The American Federation of Teachers (AFT) recently commissioned a study to review the research that finds liberal bias run amok in academe. Believing that the AFT is not a dispassionate observer of this debate, this article provides "The Chronicle of Higher Education's" survey of the genre. The studies reviewed include: (1) "Political Bias in the…

  20. The Antifeminist Bias in Traditional Criticism.

    ERIC Educational Resources Information Center

    Rogers, Katharine M.

    Ten recent articles and books are cited in this paper as examples of a continuing antifeminist bias in literary criticism. Several forms of this bias are discussed, including an imperviousness to the feminist awareness, a refusal to recognize it, and open irritation by some critics that women are now finding a voice in literary criticism. A…

  1. Racially Biased Policing: Determinants of Citizen Perceptions

    ERIC Educational Resources Information Center

    Weitzer, Ronald; Tuch, Steven A.

    2005-01-01

    The current controversy surrounding racial profiling in America has focused renewed attention on the larger issue of racial bias by the police. Yet little is known about the extent of police racial bias and even less about public perceptions of the problem. This article analyzes recent national survey data on citizens' views of and reported…

  2. The Battle over Studies of Faculty Bias

    ERIC Educational Resources Information Center

    Gravois, John

    2007-01-01

    The American Federation of Teachers (AFT) recently commissioned a study to review the research that finds liberal bias run amok in academe. Believing that the AFT is not a dispassionate observer of this debate, this article provides "The Chronicle of Higher Education's" survey of the genre. The studies reviewed include: (1) "Political Bias in the…

  3. Exploratory Studies of Bias in Achievement Tests.

    ERIC Educational Resources Information Center

    Green, Donald Ross; Draper, John F.

    This paper considers the question of bias in group administered academic achievement tests, bias which is inherent in the instruments themselves. A body of data on the test of performance of three disadvantaged minority groups--northern, urban black; southern, rural black; and, southwestern, Mexican-Americans--as tryout samples in contrast to…

  4. Understanding Unconscious Bias and Unintentional Racism

    ERIC Educational Resources Information Center

    Moule, Jean

    2009-01-01

    Unconscious biases affect one's relationships, whether they are fleeting relationships in airports or longer term relationships between teachers and students, teachers and parents, teachers and other educators. In this article, the author argues that understanding one's possible biases is essential for developing community in schools.…

  5. Gender Bias: Inequities in the Classroom.

    ERIC Educational Resources Information Center

    Love, Reeve

    1993-01-01

    This article explores sex bias in curricular materials for elementary and secondary schools. Sex bias is defined as a set of unconscious behaviors that, in themselves, are often trivial and generally favorable. Although these behaviors do not hurt if they happen only once, they can cause a great deal of harm if a pattern develops that serves to…

  6. Distinctive Characteristics of Sexual Orientation Bias Crimes

    ERIC Educational Resources Information Center

    Stacey, Michele

    2011-01-01

    Despite increased attention in the area of hate crime research in the past 20 years, sexual orientation bias crimes have rarely been singled out for study. When these types of crimes are looked at, the studies are typically descriptive in nature. This article seeks to increase our knowledge of sexual orientation bias by answering the question:…

  7. How Many Hindsight Biases Are There?

    ERIC Educational Resources Information Center

    Blank, Hartmut; Nestler, Steffen; von Collani, Gernot; Fischer, Volkhard

    2008-01-01

    The answer is three: questioning a conceptual default assumption in hindsight bias research, we argue that the hindsight bias is not a unitary phenomenon but consists of three separable and partially independent subphenomena or components, namely, memory distortions, impressions of foreseeability and impressions of necessity. Following a detailed…

  8. Distinctive Characteristics of Sexual Orientation Bias Crimes

    ERIC Educational Resources Information Center

    Stacey, Michele

    2011-01-01

    Despite increased attention in the area of hate crime research in the past 20 years, sexual orientation bias crimes have rarely been singled out for study. When these types of crimes are looked at, the studies are typically descriptive in nature. This article seeks to increase our knowledge of sexual orientation bias by answering the question:…

  9. Developmental Changes in the Whole Number Bias

    ERIC Educational Resources Information Center

    Braithwaite, David W.; Siegler, Robert S.

    2017-01-01

    Many students' knowledge of fractions is adversely affected by whole number bias, the tendency to focus on the separate whole number components (numerator and denominator) of a fraction rather than on the fraction's integrated magnitude (ratio of numerator to denominator). Although whole number bias appears early in the fraction learning process…

  10. Biases in Children's and Adults' Moral Judgments

    ERIC Educational Resources Information Center

    Powell, Nina L.; Derbyshire, Stuart W. G.; Guttentag, Robert E.

    2012-01-01

    Two experiments examined biases in children's (5/6- and 7/8-year-olds) and adults' moral judgments. Participants at all ages judged that it was worse to produce harm when harm occurred (a) through action rather than inaction (omission bias), (b) when physical contact with the victim was involved (physical contact principle), and (c) when the harm…

  11. Distinctive characteristics of sexual orientation bias crimes.

    PubMed

    Stacey, Michele

    2011-10-01

    Despite increased attention in the area of hate crime research in the past 20 years, sexual orientation bias crimes have rarely been singled out for study. When these types of crimes are looked at, the studies are typically descriptive in nature. This article seeks to increase our knowledge of sexual orientation bias by answering the question: What are the differences between sexual orientation motivated bias crimes and racial bias crimes? This question is examined using data from the National Incident Based Reporting System (NIBRS) and multiple regression techniques. This analysis draws on the strengths of NIBRS to look at the incident characteristics of hate crimes and distinguishing characteristics of sexual orientation crimes. Specifically this analysis looks at the types and seriousness of offenses motivated by sexual orientation bias as opposed to race bias as well as victim and offender characteristics. The findings suggest that there are differences between these two types of bias crimes, suggesting a need for further separation of the bias types in policy and research.

  12. Attributional Biases among Clinicians and Nonclinicians.

    ERIC Educational Resources Information Center

    Harari, Oren; Hosey, Karen R.

    1981-01-01

    Clinicians and nonclinicians made causal attributions to actor behaviors. Analysis showed clear observer attribution bias for both groups. A greater bias occurred with deviant actor behavior and in situations that featured actor actions over opinions over emotions. Results are discussed in terms of applicability to clinical practice. (Author/JAC)

  13. Hindsight Bias and Developing Theories of Mind

    ERIC Educational Resources Information Center

    Bernstein, Daniel M.; Atance, Cristina; Meltzoff, Andrew N.; Loftus, Geoffrey R.

    2007-01-01

    Although "hindsight bias" (the "I knew it all along" phenomenon) has been documented in adults, its development has not been investigated. This is despite the fact that hindsight bias errors closely resemble the errors children make on theory of mind (ToM) tasks. Two main goals of the present work were to (a) create a battery of hindsight tasks…

  14. Attention bias modification: the Emperor's new suit?

    PubMed

    Emmelkamp, Paul M G

    2012-06-25

    A series of primarily laboratory-based studies found attention bias modification in socially anxious participants to lead to reduced anxiety. It is argued that the failure to replicate the positive results of attention bias modification in the study of Carlbring et al. may be due to reasons other than the application through the Internet. A number of controlled studies failed to replicate the positive effects of attention bias modification in clinically rather than subclinically socially anxious subjects. Given the lack of robust evidence for attention bias modification in clinically socially anxious individuals, the author is inclined to consider attention bias modification as 'the Emperor's new suit'. Results achieved with regular Internet-based treatments for social anxiety disorder based on cognitive therapy and exposure methods are much better than those achieved with attention bias modification procedures delivered 'face to face' in clinically distressed participants. Given the lack of robust evidence for attention bias modification in clinical samples, there is no need yet to investigate the implementation of attention bias modification through the Internet.Please see related article: http://www.biomedcentral.com/1471-244X/12/66.

  15. Definition of the Situation and Observer Bias.

    ERIC Educational Resources Information Center

    Kolman, Anita Sue

    An experiment is reported in which an attempt was made to bias college students' observations of a videotape of children at play. The study is framed in terms of W.I. Thomas' ideas concerning the definition of the situation. Observer bias is an instance when a definition of a situation is based primarily on subjective situational factors. Reliance…

  16. Belief biases and volatility of assets

    NASA Astrophysics Data System (ADS)

    Lei-Sun, Wen-Zou, Hui

    2014-10-01

    Based on an overlapping generation model, this paper introduces the noise traders with belief biases and rational traders. With an equilibrium analysis, this paper examines the volatility of risky asset. The results show that the belief biases, the probability of economy state, and the domain capability are all the factors that have effects on the volatility of the market.

  17. Developmental Changes in the Whole Number Bias

    ERIC Educational Resources Information Center

    Braithwaite, David W.; Siegler, Robert S.

    2017-01-01

    Many students' knowledge of fractions is adversely affected by whole number bias, the tendency to focus on the separate whole number components (numerator and denominator) of a fraction rather than on the fraction's integrated magnitude (ratio of numerator to denominator). Although whole number bias appears early in the fraction learning process…

  18. An Iterative Item Bias Detection Method.

    ERIC Educational Resources Information Center

    Van Der Flier, Henk; And Others

    1984-01-01

    Two strategies for assessing item bias are discussed: methods comparing item difficulties unconditional on ability and methods comparing probabilities of response conditional on ability. Results suggest that the iterative logit method is an improvement on the noniterative one and is efficient in detecting biased and unbiased items. (Author/DWH)

  19. Systematic Error Modeling and Bias Estimation

    PubMed Central

    Zhang, Feihu; Knoll, Alois

    2016-01-01

    This paper analyzes the statistic properties of the systematic error in terms of range and bearing during the transformation process. Furthermore, we rely on a weighted nonlinear least square method to calculate the biases based on the proposed models. The results show the high performance of the proposed approach for error modeling and bias estimation. PMID:27213386

  20. Systematic Error Modeling and Bias Estimation.

    PubMed

    Zhang, Feihu; Knoll, Alois

    2016-05-19

    This paper analyzes the statistic properties of the systematic error in terms of range and bearing during the transformation process. Furthermore, we rely on a weighted nonlinear least square method to calculate the biases based on the proposed models. The results show the high performance of the proposed approach for error modeling and bias estimation.

  1. Full Electric Control of Exchange Bias

    NASA Astrophysics Data System (ADS)

    Wu, S. M.; Cybart, Shane A.; Yi, D.; Parker, James M.; Ramesh, R.; Dynes, R. C.

    2013-02-01

    We report the creation of a multiferroic field effect device with a BiFeO3 (BFO) (antiferromagnetic-ferroelectric) gate dielectric and a La0.7Sr0.3MnO3 (LSMO) (ferromagnetic) conducting channel that exhibits direct, bipolar electrical control of exchange bias. We show that exchange bias is reversibly switched between two stable states with opposite exchange bias polarities upon ferroelectric poling of the BFO. No field cooling, temperature cycling, or additional applied magnetic or electric field beyond the initial BFO polarization is needed for this bipolar modulation effect. Based on these results and the current understanding of exchange bias, we propose a model to explain the control of exchange bias. In this model the coupled antiferromagnetic-ferroelectric order in BFO along with the modulation of interfacial exchange interactions due to ionic displacement of Fe3+ in BFO relative to Mn3+/4+ in LSMO cause bipolar modulation.

  2. Adaptive Variable Bias Magnetic Bearing Control

    NASA Technical Reports Server (NTRS)

    Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

    1998-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called Adaptive Variable Bias Control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent, time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical, computer simulation, and experimental results are presented in this paper.

  3. Are all biases missing data problems?

    PubMed

    Howe, Chanelle J; Cain, Lauren E; Hogan, Joseph W

    2015-09-01

    Estimating causal effects is a frequent goal of epidemiologic studies. Traditionally, there have been three established systematic threats to consistent estimation of causal effects. These three threats are bias due to confounders, selection, and measurement error. Confounding, selection, and measurement bias have typically been characterized as distinct types of biases. However, each of these biases can also be characterized as missing data problems that can be addressed with missing data solutions. Here we describe how the aforementioned systematic threats arise from missing data as well as review methods and their related assumptions for reducing each bias type. We also link the assumptions made by the reviewed methods to the missing completely at random (MCAR) and missing at random (MAR) assumptions made in the missing data framework that allow for valid inferences to be made based on the observed, incomplete data.

  4. Sampling Bias on Cup Anemometer Mean Winds

    NASA Astrophysics Data System (ADS)

    Kristensen, L.; Hansen, O. F.; Højstrup, J.

    2003-10-01

    The cup anemometer signal can be sampled in several ways to obtain the mean wind speed. Here we discuss the sampling of series of mean wind speeds from consecutive rotor rotations, followed by unweighted and weighted averaging. It is shown that the unweighted averaging creates a positive bias on the long-term mean wind speed, which is at least one order of magnitude larger than the positive bias from the weighted averaging, also known as the sample-and-hold method. For a homogeneous, neutrally stratified flow the first biases are 1%-2%. For comparison the biases due to fluctuations of the three wind velocity components and due to calibration non-linearity are determined under the same conditions. The largest of these is the v-bias from direction fluctuations. The calculations pertain to the Risø P2546A model cup anemometer.

  5. G Protein-Coupled Receptor Biased Agonism

    PubMed Central

    Hodavance, Sima Y.; Gareri, Clarice; Torok, Rachel D.; Rockman, Howard A.

    2016-01-01

    G protein-coupled receptors (GPCR) are the largest family of targets for current therapeutics. The classic model of their activation was binary, where agonist binding induced an active conformation and subsequent downstream signaling. Subsequently, the revised concept of biased agonism emerged, where different ligands at the same GPCR selectively activate one downstream pathway versus another. Advances in understanding the mechanism of biased agonism has led to the development of novel ligands, which have the potential for improved therapeutic and safety profiles. In this review, we summarize the theory and most recent breakthroughs in understanding biased signaling, examine recent laboratory investigations concerning biased ligands across different organ systems, and discuss the promising clinical applications of biased agonism. PMID:26751266

  6. Implicit Social Biases in People With Autism.

    PubMed

    Birmingham, Elina; Stanley, Damian; Nair, Remya; Adolphs, Ralph

    2015-11-01

    Implicit social biases are ubiquitous and are known to influence social behavior. A core diagnostic criterion of autism spectrum disorders (ASD) is abnormal social behavior. We investigated the extent to which individuals with ASD might show a specific attenuation of implicit social biases, using Implicit Association Tests (IATs) involving social (gender, race) and nonsocial (nature, shoes) categories. High-functioning adults with ASD showed intact but reduced IAT effects relative to healthy control participants. We observed no selective attenuation of implicit social (vs. nonsocial) biases in our ASD population. To extend these results, we supplemented our healthy control data with data collected from a large online sample from the general population and explored correlations between autistic traits and IAT effects. We observed no systematic relationship between autistic traits and implicit social biases in our online and control samples. Taken together, these results suggest that implicit social biases, as measured by the IAT, are largely intact in ASD. © The Author(s) 2015.

  7. Cognitive bias modification approaches to anxiety.

    PubMed

    MacLeod, Colin; Mathews, Andrew

    2012-01-01

    Clinical anxiety disorders and elevated levels of anxiety vulnerability are characterized by cognitive biases, and this processing selectivity has been implicated in theoretical accounts of these conditions. We review research that has sought to evaluate the causal contributions such biases make to anxiety dysfunction and to therapeutically alleviate anxiety using cognitive-bias modification (CBM) procedures. After considering the purpose and nature of CBM methodologies, we show that variants designed to modify selective attention (CBM-A) or interpretation (CBM-I) have proven capable of reducing anxiety vulnerability and ameliorating dysfunctional anxiety. In addition to supporting the causal role of cognitive bias in anxiety vulnerability and dysfunction and illuminating the mechanisms that underpin such bias, the findings suggest that CBM procedures may have therapeutic promise within clinical settings. We discuss key issues within this burgeoning field of research and suggest future directions CBM research should take to maximize its theoretical and applied value.

  8. A catalog of biases in questionnaires.

    PubMed

    Choi, Bernard C K; Pak, Anita W P

    2005-01-01

    Bias in questionnaires is an important issue in public health research. To collect the most accurate data from respondents, investigators must understand and be able to prevent or at least minimize bias in the design of their questionnaires. This paper identifies and categorizes 48 types of bias in questionnaires based on a review of the literature and offers an example of each type. The types are categorized according to three main sources of bias: the way a question is designed, the way the questionnaire as a whole is designed, and how the questionnaire is administered. This paper is intended to help investigators in public health understand the mechanism and dynamics of problems in questionnaire design and to provide a checklist for identifying potential bias in a questionnaire before it is administered.

  9. Evidence Of Nationalistic Bias In Muaythai

    PubMed Central

    Myers, Tony D.; Balmer, Nigel J.; Nevill, Alan M.; Nakeeb, Yahya Al

    2006-01-01

    MuayThai is a combat sport with a growing international profile but limited research conducted into judging practices and processes. Problems with judging of other subjectively judged combat sports have caused controversy at major international tournaments that have resulted in changes to scoring methods. Nationalistic bias has been central to these problems and has been identified across a range of sports. The aim of this study was to examine nationalistic bias in MuayThai. Data were collected from the International Federation of MuayThai Amateur (IFMA) World Championships held in Almaty, Kazakhstan September 2003 and comprised of tournament results from 70 A-class MuayThai bouts each judged by between five and nine judges. Bouts examined featured 62 competitors from 21 countries and 25 judges from 11 countries. Results suggested that nationalistic bias was evident. The bias observed equated to approximately one round difference between opposing judges over the course of a bout (a mean of 1.09 (SE=0.50) points difference between judges with opposing affilations). The number of neutral judges used meant that this level of bias generally did not influence the outcome of bouts. Future research should explore other ingroup biases, such as nearest neighbour bias and political bias as well as investigating the feasibility adopting an electronic scoring system. Key Points Nationalistic bias is evident in international amateur MuayThai judging. The impact on the outcome of bouts is limited. The practice of using a large number of neutral judges appears to reduce the impact of nationalistic bias. PMID:24357972

  10. Medical journal peer review: process and bias.

    PubMed

    Manchikanti, Laxmaiah; Kaye, Alan D; Boswell, Mark V; Hirsch, Joshua A

    2015-01-01

    Scientific peer review is pivotal in health care research in that it facilitates the evaluation of findings for competence, significance, and originality by qualified experts. While the origins of peer review can be traced to the societies of the eighteenth century, it became an institutionalized part of the scholarly process in the latter half of the twentieth century. This was a response to the growth of research and greater subject specialization. With the current increase in the number of specialty journals, the peer review process continues to evolve to meet the needs of patients, clinicians, and policy makers. The peer review process itself faces challenges. Unblinded peer review might suffer from positive or negative bias towards certain authors, specialties, and institutions. Peer review can also suffer when editors and/or reviewers might be unable to understand the contents of the submitted manuscript. This can result in an inability to detect major flaws, or revelations of major flaws after acceptance of publication by the editors. Other concerns include potentially long delays in publication and challenges uncovering plagiarism, duplication, corruption and scientific misconduct. Conversely, a multitude of these challenges have led to claims of scientific misconduct and an erosion of faith. These challenges have invited criticism of the peer review process itself. However, despite its imperfections, the peer review process enjoys widespread support in the scientific community. Peer review bias is one of the major focuses of today's scientific assessment of the literature. Various types of peer review bias include content-based bias, confirmation bias, bias due to conservatism, bias against interdisciplinary research, publication bias, and the bias of conflicts of interest. Consequently, peer review would benefit from various changes and improvements with appropriate training of reviewers to provide quality reviews to maintain the quality and integrity of

  11. Transition-transversion bias is not universal: a counter example from grasshopper pseudogenes.

    PubMed

    Keller, Irene; Bensasson, Douda; Nichols, Richard A

    2007-02-02

    Comparisons of the DNA sequences of metazoa show an excess of transitional over transversional substitutions. Part of this bias is due to the relatively high rate of mutation of methylated cytosines to thymine. Postmutation processes also introduce a bias, particularly selection for codon-usage bias in coding regions. It is generally assumed, however, that there is a universal bias in favour of transitions over transversions, possibly as a result of the underlying chemistry of mutation. Surprisingly, this underlying trend has been evaluated only in two types of metazoan, namely Drosophila and the Mammalia. Here, we investigate a third group, and find no such bias. We characterize the point substitution spectrum in Podisma pedestris, a grasshopper species with a very large genome. The accumulation of mutations was surveyed in two pseudogene families, nuclear mitochondrial and ribosomal DNA sequences. The cytosine-guanine (CpG) dinucleotides exhibit the high transition frequencies expected of methylated sites. The transition rate at other cytosine residues is significantly lower. After accounting for this methylation effect, there is no significant difference between transition and transversion rates. These results contrast with reports from other taxa and lead us to reject the hypothesis of a universal transition/transversion bias. Instead we suggest fundamental interspecific differences in point substitution processes.

  12. Auditory Localisation Biases Increase with Sensory Uncertainty

    PubMed Central

    Garcia, Sara E.; Jones, Pete R.; Rubin, Gary S.; Nardini, Marko

    2017-01-01

    Psychophysical studies have frequently found that adults with normal hearing exhibit systematic errors (biases) in their auditory localisation judgments. Here we tested (i) whether systematic localisation errors could reflect reliance on prior knowledge, as has been proposed for other systematic perceptual biases, and (ii) whether auditory localisation biases can be reduced following training with accurate visual feedback. Twenty-four normal hearing participants were asked to localise the position of a noise burst along the azimuth before, during, and after training with visual feedback. Consistent with reliance on prior knowledge to reduce sensory uncertainty, we found that auditory localisation biases increased when auditory localisation uncertainty increased. Specifically, participants mis-localised auditory stimuli as being more eccentric than they were, and did so more when auditory uncertainty was greater. However, biases also increased with eccentricity, despite no corresponding increase in uncertainty, which is not readily explained by use of a simple prior favouring peripheral locations. Localisation biases decreased (improved) following training with visual feedback, but the reliability of the visual feedback stimulus did not change the effects of training. We suggest that further research is needed to identify alternative mechanisms, besides use of prior knowledge, that could account for increased perceptual biases under sensory uncertainty. PMID:28074913

  13. Oceanic origin of southeast tropical Atlantic biases

    NASA Astrophysics Data System (ADS)

    Xu, Zhao; Li, Mingkui; Patricola, Christina M.; Chang, Ping

    2014-12-01

    Most coupled general circulation models suffer from a prominent warm sea surface temperature bias in the southeast tropical Atlantic Ocean off the coast of Africa. The origin of the bias is not understood and remains highly controversial. Previous studies suggest that the origin of the bias stems from systematic errors of atmospheric models in simulating surface heat flux and coastal wind, or poorly simulated coastal upwelling. In this study, we show, using different reanalysis and observational data sets combined with a set of eddy-resolving regional ocean model simulations, that systematic errors in ocean models also make a significant contribution to the bias problem. In particular (1) the strong warm bias at the Angola-Benguela front that is maintained by the local wind and the convergence of Angola and Benguela Currents is caused by an overshooting of the Angola Current in ocean models and (2) the alongshore warm bias to the south of the front is caused by ocean model deficiencies in simulating the sharp thermocline along the Angola coast, which is linked to biases in the equatorial thermocline, and the complex circulation system within the Benguela upwelling zone.

  14. [Practical considerations on detection of publication bias].

    PubMed

    Palma Pérez, Silvia; Delgado Rodríguez, Miguel

    2006-12-01

    The present review aims to answer 3 questions: does publication bias need to be assessed in meta-analyses?; what procedures, not requiring complex statistical approaches, can be applied to detect it?; and should other factors be taken into account when interpreting the procedures? The first question is easy to answer. Publication bias is a potential threat to the validity of the conclusions of meta-analyses. Therefore, both the MOOSE and QUOROM statements include publication bias in their guidelines; nevertheless, many meta-analyses do not use these statements (e.g., meta-analyses conducted by the Cochrane Collaboration), perhaps because they use a comprehensive search strategy. There are many methods to assess publication bias. The most frequently used are funnel plots or , (which allow the effects of bias to be estimated), and methods based upon regression on plots, such as Egger's method and funnel plot regression. An advantage of these methods is that they can only be applied using published data. However, agreement between these methods in detecting bias is often poor. Therefore, application of more than one method to detect publication bias is recommended. To correctly interpret the results, the number of pooled studies should be more than 10 and the existence of heterogeneity in the pooled estimate must be taken into account.

  15. Biases in GNSS-Data Processing

    NASA Astrophysics Data System (ADS)

    Schaer, S. C.; Dach, R.; Lutz, S.; Meindl, M.; Beutler, G.

    2010-12-01

    Within the Global Positioning System (GPS) traditionally different types of pseudo-range measurements (P-code, C/A-code) are available on the first frequency that are tracked by the receivers with different technologies. For that reason, P1-C1 and P1-P2 Differential Code Biases (DCB) need to be considered in a GPS data processing with a mix of different receiver types. Since the Block IIR-M series of GPS satellites also provide C/A-code on the second frequency, P2-C2 DCB need to be added to the list of biases for maintenance. Potential quarter-cycle biases between different phase observables (specifically L2P and L2C) are another issue. When combining GNSS (currently GPS and GLONASS), careful consideration of inter-system biases (ISB) is indispensable, in particular when an adequate combination of individual GLONASS clock correction results from different sources (using, e.g., different software packages) is intended. Facing the GPS and GLONASS modernization programs and the upcoming GNSS, like the European Galileo and the Chinese Compass, an increasing number of types of biases is expected. The Center for Orbit Determination in Europe (CODE) is monitoring these GPS and GLONASS related biases for a long time based on RINEX files of the tracking network of the International GNSS Service (IGS) and in the frame of the data processing as one of the global analysis centers of the IGS. Within the presentation we give an overview on the stability of the biases based on the monitoring. Biases derived from different sources are compared. Finally, we give an outlook on the potential handling of such biases with the big variety of signals and systems expected in the future.

  16. Semiparametric Regression in Size-Biased Sampling

    PubMed Central

    Chen, Ying Qing

    2009-01-01

    Summary Size-biased sampling arises when a positive-valued outcome variable is sampled with selection probability proportional to its size. In this article, we propose a semiparametric linear regression model to analyze size-biased outcomes. In our proposed model, the regression parameters of the covariates are of major interest, while the distribution of random errors is unspecified. Under the proposed model, we discover that the regression parameters are invariant regardless of size-biased sampling. Following this invariance property, we develop a simple estimation procedure for inferences. Our proposed methods are evaluated in simulation studies and applied to two real data analyses. PMID:19432792

  17. Removing Malmquist bias from linear regressions

    NASA Technical Reports Server (NTRS)

    Verter, Frances

    1993-01-01

    Malmquist bias is present in all astronomical surveys where sources are observed above an apparent brightness threshold. Those sources which can be detected at progressively larger distances are progressively more limited to the intrinsically luminous portion of the true distribution. This bias does not distort any of the measurements, but distorts the sample composition. We have developed the first treatment to correct for Malmquist bias in linear regressions of astronomical data. A demonstration of the corrected linear regression that is computed in four steps is presented.

  18. Bounding the bias of contrastive divergence learning.

    PubMed

    Fischer, Asja; Igel, Christian

    2011-03-01

    Optimization based on k-step contrastive divergence (CD) has become a common way to train restricted Boltzmann machines (RBMs). The k-step CD is a biased estimator of the log-likelihood gradient relying on Gibbs sampling. We derive a new upper bound for this bias. Its magnitude depends on k, the number of variables in the RBM, and the maximum change in energy that can be produced by changing a single variable. The last reflects the dependence on the absolute values of the RBM parameters. The magnitude of the bias is also affected by the distance in variation between the modeled distribution and the starting distribution of the Gibbs chain.

  19. Trends in source gases

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

    1989-01-01

    Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

  20. Exploration of Temporal ICD Coding Bias Related to Acute Diabetic Conditions

    PubMed Central

    McKillop, Mollie; Polubriaginof, Fernanda; Weng, Chunhua

    2015-01-01

    Electronic Health Records (EHRs) hold great promise for secondary data reuse but have been reported to contain severe biases. The temporal characteristics of coding biases remain unclear. This study used a survival analysis approach to reveal temporal bias trends for coding acute diabetic conditions among 268 diabetes patients. For glucose-controlled ketoacidosis patients we found it took an average of 7.5 months for the incorrect code to be removed, while for glucose-controlled hypoglycemic patients it took an average of 9 months. We also examined blood glucose lab values and performed a case review to confirm the validity of our findings. We discuss the implications of our findings and propose future work. PMID:26958300

  1. Verb bias and verb-specific competition effects on sentence production

    PubMed Central

    Thothathiri, Malathi; Evans, Daniel G.; Poudel, Sonali

    2017-01-01

    How do speakers choose between structural options for expressing a given meaning? Overall preference for some structures over others as well as prior statistical association between specific verbs and sentence structures (“verb bias”) are known to broadly influence language use. However, the effects of prior statistical experience on the planning and execution of utterances and the mechanisms that facilitate structural choice for verbs with different biases have not been fully explored. In this study, we manipulated verb bias for English double-object (DO) and prepositional-object (PO) dative structures: some verbs appeared solely in the DO structure (DO-only), others solely in PO (PO-only) and yet others equally in both (Equi). Structural choices during subsequent free-choice sentence production revealed the expected dispreference for DO overall but critically also a reliable linear trend in DO production that was consistent with verb bias (DO-only > Equi > PO-only). Going beyond the general verb bias effect, three results suggested that Equi verbs, which were associated equally with the two structures, engendered verb-specific competition and required additional resources for choosing the dispreferred DO structure. First, DO production with Equi verbs but not the other verbs correlated with participants’ inhibition ability. Second, utterance duration prior to the choice of a DO structure showed a quadratic trend (DO-only < Equi > PO-only) with the longest durations for Equi verbs. Third, eye movements consistent with reimagining the event also showed a quadratic trend (DO-only < Equi > PO-only) prior to choosing DO, suggesting that participants used such recall particularly for Equi verbs. Together, these analyses of structural choices, utterance durations, eye movements and individual differences in executive functions shed light on the effects of verb bias and verb-specific competition on sentence production and the role of different executive functions

  2. Assessing the impact of satellite-based observations in sea surface temperature trends

    NASA Astrophysics Data System (ADS)

    Huang, Boyin; Liu, Chunying; Banzon, Viva F.; Zhang, Huai-Min; Karl, Thomas R.; Lawrimore, Jay H.; Vose, Russell S.

    2016-04-01

    Global trends of sea surface temperature (SST) are assessed for the existing and new experimental SST analyses that incorporate advanced very high resolution radiometer (AVHRR) observations from NOAA polar-orbiting satellites. These analyses show that globally and annually averaged SST trends over the 21st century (2000-2015) are similar to the trends for the full satellite record period (1982-2015), regardless of whether AVHRR data are included in the analyses. It is shown that appropriate bias correction is an important step to remove discontinuities of AVHRR data for consistent time series and trend analysis.

  3. Time scale bias in erosion rates of glaciated landscapes

    PubMed Central

    Ganti, Vamsi; von Hagke, Christoph; Scherler, Dirk; Lamb, Michael P.; Fischer, Woodward W.; Avouac, Jean-Philippe

    2016-01-01

    Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time. PMID:27713925

  4. Time scale bias in erosion rates of glaciated landscapes.

    PubMed

    Ganti, Vamsi; von Hagke, Christoph; Scherler, Dirk; Lamb, Michael P; Fischer, Woodward W; Avouac, Jean-Philippe

    2016-10-01

    Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time.

  5. Cassini Thruster Calibration Algorithm Using Reaction Wheel Biasing Data

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen

    2012-01-01

    Thrust force estimates for the reaction control thrusters on-board Cassini spacecraft are presented in this paper. Cassini consists of two thruster branches (A and B) each with eight thrusters. The four Z-thrusters control the X and Y-axes, while the four Y-thrusters control the Z-axis. It is important to track the thrust force estimates in order to detect any thruster degradation and for supporting various activities in spacecraft operations (Titan flyby, spacecraft maneuvers). The Euler equation, which describes the rotational motion of the spacecraft during a reaction wheel bias event, is used to develop the algorithm. The thrust estimates are obtained from the pseudo inverse solution using flight telemetry during the bias. Results show that the A-branch Z3A and Z4A thrusters exhibited degraded thrust in November 2008. Due to the degraded thrust performance of Z3A and Z4A, A-branch usage was discontinued and prime branch was swapped to B-branch in March 2009. The thrust estimates from the B-branch do not show any degradation to date. The algorithm is used to trend the B-branch thrust force estimates as the mission continues.

  6. Cassini Thruster Calibration Algorithm Using Reaction Wheel Biasing Data

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen

    2012-01-01

    Thrust force estimates for the reaction control thrusters on-board Cassini spacecraft are presented in this paper. Cassini consists of two thruster branches (A and B) each with eight thrusters. The four Z-thrusters control the X and Y-axes, while the four Y-thrusters control the Z-axis. It is important to track the thrust force estimates in order to detect any thruster degradation and for supporting various activities in spacecraft operations (Titan flyby, spacecraft maneuvers). The Euler equation, which describes the rotational motion of the spacecraft during a reaction wheel bias event, is used to develop the algorithm. The thrust estimates are obtained from the pseudo inverse solution using flight telemetry during the bias. Results show that the A-branch Z3A and Z4A thrusters exhibited degraded thrust in November 2008. Due to the degraded thrust performance of Z3A and Z4A, A-branch usage was discontinued and prime branch was swapped to B-branch in March 2009. The thrust estimates from the B-branch do not show any degradation to date. The algorithm is used to trend the B-branch thrust force estimates as the mission continues.

  7. Memory effect versus exchange bias for maghemite nanoparticles

    NASA Astrophysics Data System (ADS)

    Nadeem, K.; Krenn, H.; Szabó, D. V.

    2015-11-01

    We studied the temperature dependence of memory and exchange bias effects and their dependence on each other in maghemite (γ-Fe2O3) nanoparticles by using magnetization studies. Memory effect in zero field cooled process in nanoparticles is a fingerprint of spin-glass behavior which can be due to i) surface disordered spins (surface spin-glass) and/or ii) randomly frozen and interacting nanoparticles core spins (super spin-glass). Temperature region (25-70 K) for measurements has been chosen just below the average blocking temperature (TB=75 K) of the nanoparticles. Memory effect (ME) shows a non-monotonous behavior with temperature. It shows a decreasing trend with decreasing temperature and nearly vanishes below 30 K. However it also decreased again near the blocking temperature of the nanoparticles e.g., 70 K. Exchange bias (EB) in these nanoparticles arises due to core/shell interface interactions. The EB increases sharply below 30 K due to increase in core/shell interactions, while ME starts vanishing below 30 K. We conclude that the core/shell interface interactions or EB have not enhanced the ME but may reduce it in these nanoparticles.

  8. Remote Impact of Extratropical Thermal Bias on Tropical Biases in the Norwegian Earth System Model

    NASA Astrophysics Data System (ADS)

    Koseki, Shunya; Losada, Teresa; Keenlyside, Noel; Toniazzo, Thomas; Castano-Tierno, Antonio; Rodriguez-Fonseca, Belen; Demissie, Teferi; Mechoso, Roberto

    2016-04-01

    One of large biases exhibited by most state-of-the-art coupled general circulation models (CGCMs) is warm sea surface temperature (SST) in the tropical ocean. Due to the warm SST bias, CGCMs fails to represent the location of intertropical convergence zone (ITCZ) realistically. Other common bias is warm SST over the Southern Ocean partly because of less reproduction of stratocumulus over the Southern Ocean. Some previous studies show that the ITCZ position is affected by the extratropical thermal condition. In this study, we explore a connection between the extratropical warm SST bias and tropical biases in the Norwegian Earth System Model (NorESM). The control simulation of NorESM has the common tropical biases and warm bias over the Southern Ocean. NorESM overestimates the downward shortwave radiation flux over the Southern Ocean and underestimates the low-level cloud formation (in particular, between 40S and 30S). The more incoming shortwave radiation is consistent with the warm SST bias over the Southern Ocean. We conduct a sensitivity experiment in which the incoming shortwave radiation at the top of atmosphere is reduced artificially only between 30S and 60S. The reduced shortwave radiation cools the SST in the Southern Ocean. Interestingly, the annual-mean rainfall over the tropics is reduced (amplified) to the south (north) of the equator. Especially, the double-ITCZ over the tropical Pacific Ocean is diminished in the sensitivity experiment. Moreover, warm SST biases in the tropical ocean are also reduced. Over the tropical Atlantic, the reduction of biases is more remarkable in MAM and JJA: westerly bias over the equatorial Atlantic is reduced and SST is cooler compared to control simulation. Consequently, the rainfall increases (decreases) in the north (south) of the equator, that is, the sensitivity experiment shows more realistic climatological state. This result indicates that a part of tropical biases in NorESM is associated with the warm SST bias in

  9. Gender bias in the force concept inventory?

    NASA Astrophysics Data System (ADS)

    Dietz, R. D.; Pearson, R. H.; Semak, M. R.; Willis, C. W.

    2012-02-01

    Could the well-established fact that males tend to score higher than females on the Force Concept Inventory (FCI) be due to gender bias in the questions? The eventual answer to the question hinges on the definition of bias. We assert that a question is biased only if a factor other than ability (in this case gender) affects the likelihood that a student will answer the question correctly. The statistical technique of differential item functioning allows us to control for ability in our analysis of student performance on each of the thirty FCI questions. This method uses the total score on the FCI as the measure of ability. We conclude that the evidence for gender bias in the FCI questions is marginal at best.

  10. Affective forecasting bias in preschool children.

    PubMed

    Gautam, Shalini; Bulley, Adam; von Hippel, William; Suddendorf, Thomas

    2017-03-10

    Adults are capable of predicting their emotional reactions to possible future events. Nevertheless, they systematically overestimate the intensity of their future emotional reactions relative to how they feel when these events actually occur. The developmental origin of this "intensity bias" has not yet been examined. Two studies were conducted to test the intensity bias in preschool children. In the first study, 5-year-olds (N=30) predicted how they would feel if they won or lost various games. Comparisons with subsequent self-reported feelings indicated that participants overestimated how sad they would feel to lose the games but did not overestimate their happiness from winning. The second study replicated this effect in another sample of 5-year-olds (n=34) and also found evidence of an intensity bias in 4-year-olds (n=30). These findings provide the first evidence of a negative intensity bias in affective forecasting among young children.

  11. FIP bias in a sigmoidal active region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

    2014-01-01

    We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

  12. Galaxy bias and primordial non-Gaussianity

    SciTech Connect

    Assassi, Valentin; Baumann, Daniel; Schmidt, Fabian E-mail: D.D.Baumann@uva.nl

    2015-12-01

    We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin of any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation.

  13. Exchange bias studied with polarized neutron reflectivity

    SciTech Connect

    te Velthuis, S. G. E.

    2000-01-05

    The role of Polarized Neutron Reflectivity (PNR) for studying natural and synthetic exchange biased systems is illustrated. For a partially oxidized thin film of Co, cycling of the magnetic field causes a considerable reduction of the bias, which the onset of diffuse neutron scattering shows to be due to the loosening of the ferromagnetic domains. On the other hand, PNR measurements of a model exchange bias junction consisting of an n-layered Fe/Cr antiferromagnetic (AF) superlattice coupled with an m-layered Fe/Cr ferromagnetic (F) superlattice confirm the predicted collinear magnetization in the two superlattices. The two magnetized states of the F (along or opposite to the bias field) differ only in the relative orientation of the F and adjacent AF layer. The possibility of reading clearly the magnetic state at the interface pinpoints the commanding role that PNR is having in solving this intriguing problem.

  14. Future research in weight bias: What next?

    PubMed

    Alberga, Angela S; Russell-Mayhew, Shelly; von Ranson, Kristin M; McLaren, Lindsay; Ramos Salas, Ximena; Sharma, Arya M

    2016-06-01

    The 2015 Canadian Weight Bias Summit disseminated the newest research advances and brought together 40 experts, stakeholders, and policy makers in various disciplines in health, education, and public policy to identify future research directions in weight bias. In this paper we aim to share the results of the Summit as well as encourage international and interdisciplinary research collaborations in weight bias reduction. Consensus emerged on six research areas that warrant further investigation in weight bias: costs, causes, measurement, qualitative research and lived experience, interventions, and learning from other models of discrimination. These discussions highlighted three key lessons that were informed by the Summit, namely: language matters, the voices of people living with obesity should be incorporated, and interdisciplinary stakeholders should be included. © 2016 The Obesity Society.

  15. Popularity, similarity, and the network extraversion bias.

    PubMed

    Feiler, Daniel C; Kleinbaum, Adam M

    2015-05-01

    Using the emergent friendship network of an incoming cohort of students in an M.B.A. program, we examined the role of extraversion in shaping social networks. Extraversion has two important implications for the emergence of network ties: a popularity effect, in which extraverts accumulate more friends than introverts do, and a homophily effect, in which the more similar are two people's levels of extraversion, the more likely they are to become friends. These effects result in a systematic network extraversion bias, in which people's social networks will tend to be overpopulated with extraverts and underpopulated with introverts. Moreover, the most extraverted people have the greatest network extraversion bias, and the most introverted people have the least network extraversion bias. Our finding that social networks were systematically misrepresentative of the broader social environment raises questions about whether there is a societal bias toward believing other people are more extraverted than they actually are and whether introverts are better socially calibrated than extraverts.

  16. Implicit Social Biases in People with Autism

    PubMed Central

    Birmingham, Elina; Stanley, Damian; Nair, Remya; Adolphs, Ralph

    2015-01-01

    Implicit social biases are ubiquitous and are known to influence social behavior. A core diagnostic criterion of Autism Spectrum Disorder (ASD) is abnormal social behavior. Here we investigated the extent to which individuals with ASD might show a specific attenuation of implicit social biases, using the Implicit Association Test (IAT) across Social (gender, race) and Nonsocial (flowers/insect, shoes) categories. High-functioning adults with ASD showed intact but reduced IAT effects relative to healthy controls. Importantly, we observed no selective attenuation of implicit social (vs. nonsocial) biases in our ASD population. To extend these results, we collected data from a large online sample of the general population, and explored correlations between autistic traits and IAT effects. No associations were found between autistic traits and IAT effects for any of the categories tested in our online sample. Taken together, these results suggest that implicit social biases, as measured by the IAT, are largely intact in ASD. PMID:26386014

  17. Autobiographical memory bias in social anxiety.

    PubMed

    Krans, Julie; de Bree, June; Bryant, Richard A

    2014-01-01

    In social anxiety the psychological self is closely related to the feared stimulus. Socially anxious individuals are, by definition, concerned about how the self is perceived and evaluated by others. As autobiographical memory is strongly related to views of the self it follows that biases in autobiographical memory play an important role in social anxiety. In the present study high (n = 19) and low (n = 29) socially anxious individuals were compared on autobiographical memory bias, current goals, and self-discrepancy. Individuals high in social anxiety showed a bias towards recalling more negative and more social anxiety-related autobiographical memories, reported more current goals related to overcoming social anxiety, and showed larger self-discrepancies. The pattern of results is largely in line with earlier research in individuals with PTSD and complicated grief. This suggests that the relation between autobiographical memory bias and the self is a potentially valuable trans-diagnostic factor.

  18. A Bias in the Diagnosis of Schizophrenia

    ERIC Educational Resources Information Center

    Reade, William Kent; Wertheimer, Michael

    1976-01-01

    Research shows a relationship between diagnoses of schizophrenia among twins. It was studied whether information that a twin was schizophrenic would bias diagnoses. Such information almost doubled the rater's estimates of probability of schizophrenia in a hypothetical case history. (NG)

  19. Correcting the bias against interdisciplinary research.

    PubMed

    Shapiro, Ehud

    2014-04-01

    When making decisions about funding and jobs the scientific community should recognise that most of the tools used to evaluate scientific excellence are biased in favour of established disciplines and against interdisciplinary research.

  20. Cognitive Biases in Military Decision Making

    DTIC Science & Technology

    2007-06-14

    illusionary correlation, retrievability of instances, escalation, break even, snake bite, fear of regret, and the confirmation bias. The Military Decision...correlation, retrievability of instances, escalation, break even, snake bite, fear of regret, and the confirmation bias. The Military Decision Making...Library of Congress at the end of 2000? 8. How long, in miles, is the Amazon River? 9. How fast does the earth spin at the equator? 10. How many

  1. Full Electric Field Control of Exchange Bias

    NASA Astrophysics Data System (ADS)

    Wu, Stephen

    2014-03-01

    Exchange bias is the shift of a magnetic hysteresis curve due to interfacial magnetic coupling between a ferromagnet (FM) and an antiferromagnet (AFM). This ubiquitous effect has long been used in the electronics industry to bias the magnetization of FM layers in magnetic devices. Its continued understanding is of critical importance to advance the development of future high-density magnetic storage media and other novel magnetic devices. However, due to the technological limitations of manipulating and observing an atomically thin interface, exchange bias is not well understood. In this talk we present a multiferroic field effect device with BiFeO3 (BFO) (antiferromagnetic-ferroelectric) as the gate dielectric and La0.7Sr0.3MnO3 (LSMO) (ferromagnetic) as the conducting channel, which exhibits the direct, bipolar electric control of exchange bias. Here the magnetic states at the AFM/FM interface can be directly manipulated with electric fields and the results can be observed as a change in exchange bias polarity and magnitude. Control of exchange bias at this level has significant implications because it represents a form of electric field control of magnetism and may potentially offer a route toward the eventual full electric field control of magnetization. In this device, exchange bias is reversibly switched between two stable states with opposite exchange bias polarities upon ferroelectric poling of the BFO. No field cooling, temperature cycling, or additional applied magnetic or electric field beyond BFO poling is needed for this bipolar modulation effect. Detailed temperature dependent measurements and a model will be presented which will attribute this effect to the coupled antiferromagnetic-ferroelectric order in BFO along with the modulation of interfacial exchange interactions due to ionic displacement of Fe3+ in BFO relative to Mn3 + / 4 + in LSMO.

  2. Implicit bias, awareness and imperfect cognitions.

    PubMed

    Holroyd, Jules

    2015-05-01

    Are individuals responsible for behaviour that is implicitly biased? Implicitly biased actions are those which manifest the distorting influence of implicit associations. That they express these 'implicit' features of our cognitive and motivational make up has been appealed to in support of the claim that, because individuals lack the relevant awareness of their morally problematic discriminatory behaviour, they are not responsible for behaving in ways that manifest implicit bias. However, the claim that such influences are implicit is, in fact, not straightforwardly related to the claim that individuals lack awareness of the morally problematic dimensions of their behaviour. Nor is it clear that lack of awareness does absolve from responsibility. This may depend on whether individuals culpably fail to know something that they should know. I propose that an answer to this question, in turn, depends on whether other imperfect cognitions are implicated in any lack of the relevant kind of awareness. In this paper I clarify our understanding of 'implicitly biased actions' and then argue that there are three different dimensions of awareness that might be at issue in the claim that individuals lack awareness of implicit bias. Having identified the relevant sense of awareness I argue that only one of these senses is defensibly incorporated into a condition for responsibility, rejecting recent arguments from Washington & Kelly for an 'externalist' epistemic condition. Having identified what individuals should - and can - know about their implicitly biased actions, I turn to the question of whether failures to know this are culpable. This brings us to consider the role of implicit biases in relation to other imperfect cognitions. I conclude that responsibility for implicitly biased actions may depend on answers to further questions about their relationship to other imperfect cognitions.

  3. Antiferromagnetic spin flop and exchange bias

    NASA Astrophysics Data System (ADS)

    Nogués, J.; Morellon, L.; Leighton, C.; Ibarra, M. R.; Schuller, Ivan K.

    2000-03-01

    The effect of the antiferromagnetic spin flop on exchange bias has been investigated in antiferromagnetic (MnF2)-ferromagnetic (Fe) bilayers. Cooling and measuring in fields larger than the antiferromagnetic spin-flop field, HSF, causes an irreversible reduction of the magnitude of the exchange bias field, HE. This indicates that, contrary to what is normally assumed, the interface spin structure does not remain ``frozen in'' below TN if large enough fields are applied.

  4. Questions of bias in climate models

    SciTech Connect

    Smith, Steven J.; Wigley, Tom M.; Meinshausen, Malte; Rogelj, Joeri

    2014-08-27

    The recent work by Shindell usefully contributes to the debate over estimating climate sensitivity by highlighting an important aspect of the climate system: that climate forcings that occur over land result in a more rapid temperature response than forcings that are distributed more uniformly over the globe. While, as noted in this work, simple climate models may be biased by assuming the same temperature response for all forcing agents, the implication that the MAGICC model is biased in this way is not correct.

  5. How Specific Is the Shape Bias?

    ERIC Educational Resources Information Center

    Diesendruck, Gil; Bloom, Paul

    2003-01-01

    Three studies explored whether children's tendency to extend object names on the basis of sameness of shape (shape bias) is specific to naming. Findings indicated that 2- and 3-year-olds showed shape bias both when asked to extend a novel name and when asked to select an object of the same kind as a target object; 3-year-olds also showed shape…

  6. MONTHLY AND ANNUAL BIAS IN WEEKLY (NADP/NTN) VERSUS DAILY (AIRMON) PRECIPITATION CHEMISTRY DATA IN THE EASTERN USA

    EPA Science Inventory

    Previous comparisons of the data from the National Atmospheric Deposition Program (NADP) National Trends Network (NTN) against collocated event- and daily-sampled data suggest a substantial bias in the concentration of ammonium [NH4+] and concentrations of several base cations,...

  7. Active control system trends

    NASA Technical Reports Server (NTRS)

    Yore, E. E.; Gunderson, D. C.

    1976-01-01

    The active control concepts which achieve the benefit of improved mission performance and lower cost and generate system trends towards improved dynamic performance, more integration, and digital fly by wire mechanization are described. Analytical issues and implementation requirements and tools and approaches developed to address the analytical and implementation issues are briefly discussed.

  8. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple…

  9. Global Warming Trends.

    ERIC Educational Resources Information Center

    Jones, Philip D.; Wigley, Tom M. L.

    1990-01-01

    Results from the analysis of land and marine records from the past century are presented. It is indicated that the planet earth has warmed about one-half of a degree celsius. The uncertainty of these measurements and future warming trends are discussed. (CW)

  10. [Recent demographic trends].

    PubMed

    1987-01-01

    Population dynamics in Luxembourg in 1986 are reviewed. Separate consideration is given to fertility, nuptiality and divorce, mortality, natural increase and migration, adoption, and family policy. Some consideration is given to preliminary data for 1987 and to mortality trends among those affected by compulsory labor during World War II.

  11. [Recent demographic trends].

    PubMed

    1986-01-01

    The demographic situation in Luxembourg in 1985 is reviewed. Separate consideration is given to fertility, nuptiality and divorce, mortality, and migration. Significant trends include the continued decline in fertility among the foreign population, a new peak in the number of divorces, and a decline in infant mortality to under 10 per 1,000 for the first time.

  12. Historical Trends in Childlessness

    ERIC Educational Resources Information Center

    Rowland, Donald T.

    2007-01-01

    Changes in the rates of childlessness over time are explored using European, Australian, American, and Japanese data from censuses, national registers, and large-scale surveys. The trends are remarkably similar across the countries for which data are available: a peak in childlessness rates for the 1880-1910 birth cohorts, a more or less…

  13. Children's Books: Current Trends.

    ERIC Educational Resources Information Center

    Nist, Joan Stidham

    A major trend in children's literature is the growing academic recognition of the field--indicated by the large number of new texts that have been published since 1975. Scholarly periodicals in the field have likewise grown since the 1970s. Library science, elementary education and English literature have fostered the development of children's…

  14. Trends in Biomedical Education.

    ERIC Educational Resources Information Center

    Peppas, Nicholas A.; Mallinson, Richard G.

    1982-01-01

    An analysis of trends in biomedical education within chemical education is presented. Data used for the analysis included: type/level of course, subjects taught, and textbook preferences. Results among others of the 1980 survey indicate that 28 out of 79 schools responding offer at least one course in biomedical engineering. (JN)

  15. Marketing for Camp Trends.

    ERIC Educational Resources Information Center

    Biddle, Alicia

    1998-01-01

    To effectively market a camp, current trends and issues must be considered: specialty programming, the Americans With Disabilities Act, competing recreational programs, changes in the school year, programming for seniors, and accountability. Camps should have a marketing strategy that includes public relations, a marketing plan, a pricing…

  16. Technological trends in automobiles.

    PubMed

    Horton, E J; Compton, W D

    1984-08-10

    Current technological trends in the automotive industry reflect many diverse disciplines. Electronics and microprocessors, new engine transmission concepts, composite and ceramic materials, and computer-aided design and manufacture will combine to make possible the creation of advanced automobiles offering outstanding quality, fuel economy, and performance. A projected "average" vehicle of the 1990's is described to illustrate the application of these new concepts.

  17. Trend Monitoring and Forecasting

    DTIC Science & Technology

    2015-03-11

    information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services , Directorate for Information...SUPPLEMENTARY NOTES 14. ABSTRACT Recently, almost all web services , including Twitter, Google, Internet News, and Wikipedia, analyze their user...smart service by utilizing them. In this project, we achieved the following aims: 1) identifying the relevance of trending topic to a target domain, 2

  18. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

    In this article, the author discusses the major technical issues, products, and practices of the day. The top ten tech trends are listed and discussed. These include: (1) data mining; (2) cyberbullying; (3) 21st century skills; (4) digital content; (5) learning at leisure; (6) personal responders; (7) mobile tools; (8) bandwidth; (9) open-source…

  19. Trends in Therapeutic Recreation.

    ERIC Educational Resources Information Center

    Smith, Ralph W.

    1995-01-01

    Discusses the implications of the rapid, dramatic changes taking place in therapeutic recreation for individuals with physical disabilities. The article notes the impact of changes in managed care, examines programming trends in therapeutic recreation (adventure/outdoor education, competitive sports, handcycling, health enhancement activities, and…

  20. Travel and tourism trends

    Treesearch

    Deborah J. Chavez

    1995-01-01

    Demographic trends which impact leisure time activities are highlighted, with particular emphasis given to the impacts of the growth of minority populations. Data was collected from recreationists to National Forests and from residents of an urban community. The data indicate a shift in outdoor recreation activities.

  1. Locker Room Design Trends.

    ERIC Educational Resources Information Center

    Wiens, Janet

    2001-01-01

    Examines how today's college and university athletic locker rooms have become sophisticated recruiting tools that rival many professional facilities. Locker room design and location and their level of furniture, finishes, and equipment are discussed as is the trend for more environmentally friendly locker rooms. (GR)

  2. Trends in Interior Environments.

    ERIC Educational Resources Information Center

    Hovey, Robyn

    2000-01-01

    Examines how an understanding of interior design trends can help planners address their present and future furniture needs. Examines how new types of construction and their associated concerns are requiring new approaches from the facility designers and manufacturers of product solutions. (GR)

  3. Trends and Issues.

    ERIC Educational Resources Information Center

    Orey, Michael; Molenda, Michael; Sullivan, Michael; Klein, James D.; Brinkerfhoff, Jonathan; Koroghlanian, Carol; Moore, D. Michael; Lockee, Barbara B.; Burton, John K.; Liu, Y.; Emerson, John D.; Boes, Lisa; Mosteller, Frederick; Ely, Donald P.; Belanger, Yvonne; Ellsworth, James B.; Lowe, Carrie A.; Russell, Shayne; Thomas, Lajeane; Richey, Rita C.; Earle, Rodney S.

    2002-01-01

    The articles in this section of "Educational Media and Technology Yearbook" identify current trends and issues in the field of instructional technology. Two subsections are also included: ERIC Digests, which are reprints of ERIC reports available on the Internet, and a subsection on a variety of standards that emerged during the past…

  4. Trends in Delaware's Forests

    Treesearch

    Northeastern Research Station

    2002-01-01

    Forests protect watersheds, provide opportunities for recreation and settings for aesthetic enjoyment, serve as habitat for wildlife, and produce wood and other forest products. The forests of Delaware contribute greatly to the quality of life of the residents, making the State a better place in which to live. This brochure highlights significant trends in Delaware?s...

  5. Outdoor recreation participation trends

    Treesearch

    H. Ken Cordell; Barbara L. McDonald; R. Jeff Teasley; John C. Bergstrom; Jack Martin; Jim Bason; Vernon R. Leeworthy

    1999-01-01

    As part of the national assessment of outdoor recreation trends, the authors have taken a look at participation patterns and levels of participation across activities and across segments of our society. The primary source of data is the National Survey on Recreation and the Environment (NSRE). The NSRE is the latest in the continuing series of National Recreation...

  6. Five Trends for Schools

    ERIC Educational Resources Information Center

    Lapkoff, Shelley; Li, Rose Maria

    2007-01-01

    The authors look at important demographic trends that will have an effect on schools, including roller-coaster enrollments and increasing diversity. For example, compared with 10 years ago, the average child entering a U.S. school today is less likely to live in a family with two married parents but is more likely to have a living grandparent,…

  7. Population Trends and Prospects.

    ERIC Educational Resources Information Center

    Mauldin, W. Parker

    1980-01-01

    Future trends in population are described as they relate to developed and developing nations. It is suggested that for the next 20 years there will be a decrease in population growth rates for all areas of the world except Africa. (Author/SA)

  8. Trends in Educational Expenditure.

    ERIC Educational Resources Information Center

    Burke, Gerald

    This study provides an overview of expenditures for education and training by educational institutions in Australia, 1991-2001. The study used newly available data from the Australian Bureau of Statistics (ABS) and administrative data from the main sectors' reports on the size and trends in public and private education expenditures. It analyzed…

  9. Trends in Biomedical Education.

    ERIC Educational Resources Information Center

    Peppas, Nicholas A.; Mallinson, Richard G.

    1982-01-01

    An analysis of trends in biomedical education within chemical education is presented. Data used for the analysis included: type/level of course, subjects taught, and textbook preferences. Results among others of the 1980 survey indicate that 28 out of 79 schools responding offer at least one course in biomedical engineering. (JN)

  10. Trends Reshaping Colleges.

    ERIC Educational Resources Information Center

    Campbell, Dale F.; Peek, Roger C.

    2002-01-01

    Examines current educational trends in the community colleges, based on critical issues addressed at the 2002 Community College Futures Assembly (CCFA) in Orlando, Florida. Describes the CCFA as an independent policy forum, sponsored by the University of Florida, that convenes annually. Discusses the top three critical issues presented: the needs…

  11. Evaluation of Project Trend.

    ERIC Educational Resources Information Center

    Unco, Inc., Washington, DC.

    This report is a descriptive evaluation of the five pilot sites of Project TREND (Targeting Resources on the Educational Needs of the Disadvantaged). The five Local Education Agency (LEA) pilot sites are the educational systems of: (1) Akron, Ohio; (2) El Paso, Texas; (3) Newark, New Jersey; (4) Portland, Oregon; and, (5) San Jose (Unified),…

  12. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

    In this article, the author discusses the major technical issues, products, and practices of the day. The top ten tech trends are listed and discussed. These include: (1) data mining; (2) cyberbullying; (3) 21st century skills; (4) digital content; (5) learning at leisure; (6) personal responders; (7) mobile tools; (8) bandwidth; (9) open-source…

  13. Locker Room Design Trends.

    ERIC Educational Resources Information Center

    Wiens, Janet

    2001-01-01

    Examines how today's college and university athletic locker rooms have become sophisticated recruiting tools that rival many professional facilities. Locker room design and location and their level of furniture, finishes, and equipment are discussed as is the trend for more environmentally friendly locker rooms. (GR)

  14. Today's Recruitment Trends.

    ERIC Educational Resources Information Center

    Sugarman, Joe

    1996-01-01

    Five trends in the creation of college student recruitment publications are identified: (1) using market research and marketing principles; (2) targeting specific groups; (3) honesty about campus personality and reputation; (4) cost-effectiveness; and (5) creativity in using effective copy and design. (MSE)

  15. The Top Ten Trends.

    ERIC Educational Resources Information Center

    Bassi, Laurie J.; And Others

    1996-01-01

    Trends shaping the workplace are increased skill requirements; more educated, diverse work force; continued corporate restructuring; change in size and composition of training departments; instructional technology advances; new training delivery methods; focus on performance improvement; integrated high-performance work systems; companies becoming…

  16. Trends and Issues.

    ERIC Educational Resources Information Center

    Orey, Michael; Sullivan, Michael; Molenda, Michael; Foley, Anne L.; Morgan, Janet; McKenney, Susan; Harada, Violet H.; Lee, Jung

    2003-01-01

    Contains five articles covering general trends and issues in instructional technology, including: developments in corporate training, higher education, and K-12 education; women's contributions to the leading instructional technology journals; developing science education materials via computer-based support; learning in the Information Age; and…

  17. Global Warming Trends.

    ERIC Educational Resources Information Center

    Jones, Philip D.; Wigley, Tom M. L.

    1990-01-01

    Results from the analysis of land and marine records from the past century are presented. It is indicated that the planet earth has warmed about one-half of a degree celsius. The uncertainty of these measurements and future warming trends are discussed. (CW)

  18. Language Trends 2010 Secondary

    ERIC Educational Resources Information Center

    CILT, the National Centre for Languages, 2010

    2010-01-01

    The Language Trends survey is run jointly each year by CILT, the National Centre for Languages, the Association for Language Learning (ALL) and the Independent Schools Modern Languages Association (ISMLA). In this period of rapid change and policy development, it is vital to have an up to date picture of current issues for languages. Therefore,…

  19. Five Trends for Schools

    ERIC Educational Resources Information Center

    Lapkoff, Shelley; Li, Rose Maria

    2007-01-01

    The authors look at important demographic trends that will have an effect on schools, including roller-coaster enrollments and increasing diversity. For example, compared with 10 years ago, the average child entering a U.S. school today is less likely to live in a family with two married parents but is more likely to have a living grandparent,…

  20. Rural Conditions and Trends.

    ERIC Educational Resources Information Center

    Mazie, Sara Mills, Ed.; And Others

    1990-01-01

    This U.S. Department of Agriculture periodical gives current statistical information on rural America. This issue contains articles about the impact on rural areas of economic trends, employment, and industry changes. A general overview indicates that moderate improvements in rural employment since 1986 have been tempered by slow income growth.…

  1. Trends in Rehabilitation

    ERIC Educational Resources Information Center

    Sink, Jack

    1977-01-01

    Discusses major potential trends in rehabilitation (identified through informal interviews with 94 individuals representing various organizations, progessions, or programs) e.g., services for the severely handicapped, return to the vocational emphasis, increased interagency cooperation, and consumer involvement. Modification of programs as a…

  2. Trends in Anthropology, #116.

    ERIC Educational Resources Information Center

    Belshaw, Cyril; And Others

    1988-01-01

    This theme issue focuses on trends and future perspectives in the field of anthropology. Articles include "Challenges for the Future of Social and Cultural Anthropology"; "Anthropology in the Twenty-First Century"; "A New Interdisciplinary Impulse and the Anthropology of the 1990s"; and "Liberation Anthropology for the Year 2000." (GEA)

  3. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple…

  4. Children's Books: Current Trends.

    ERIC Educational Resources Information Center

    Nist, Joan Stidham

    A major trend in children's literature is the growing academic recognition of the field--indicated by the large number of new texts that have been published since 1975. Scholarly periodicals in the field have likewise grown since the 1970s. Library science, elementary education and English literature have fostered the development of children's…

  5. Investigating bias in squared regression structure coefficients.

    PubMed

    Nimon, Kim F; Zientek, Linda R; Thompson, Bruce

    2015-01-01

    The importance of structure coefficients and analogs of regression weights for analysis within the general linear model (GLM) has been well-documented. The purpose of this study was to investigate bias in squared structure coefficients in the context of multiple regression and to determine if a formula that had been shown to correct for bias in squared Pearson correlation coefficients and coefficients of determination could be used to correct for bias in squared regression structure coefficients. Using data from a Monte Carlo simulation, this study found that squared regression structure coefficients corrected with Pratt's formula produced less biased estimates and might be more accurate and stable estimates of population squared regression structure coefficients than estimates with no such corrections. While our findings are in line with prior literature that identified multicollinearity as a predictor of bias in squared regression structure coefficients but not coefficients of determination, the findings from this study are unique in that the level of predictive power, number of predictors, and sample size were also observed to contribute bias in squared regression structure coefficients.

  6. Oceanic Origin of Tropical Atlantic SST Biases

    NASA Astrophysics Data System (ADS)

    Chang, P.; Xu, Z.; Li, M.; Patricola, C. M.

    2012-12-01

    Most coupled general circulation models (CGCMs) suffer from a prominent warm sea surface temperature (SST) bias in the southeastern tropical Atlantic Ocean off the coast of Africa. The origin of the bias is not understood and remains highly controversial. Previous studies suggest that the origin of the bias stems from systematic errors of atmospheric models in simulating surface heat flux and coastal wind, or poorly simulated coastal upwelling. In this study, we show, using different reanalysis and observational data sets combined with a set of eddy-resolving regional ocean model simulations, that systematic errors in ocean models also make a significant contribution to the bias problem. In particular, (1) the strong warm bias at the Angola Benguela front that is maintained by the local wind and the convergence of Angola and Benguela Current is caused by an overshooting of the Angola Current in ocean models and (2) the alongshore warm bias to the south of the front is caused by ocean model deficiencies in simulating the sharp thermocline along the equator, the strong thermal gradient beneath the Angola current, and the complex circulation system within the Benguela upwelling zone.

  7. Confounding and bias in the attributable fraction.

    PubMed

    Darrow, Lyndsey A; Steenland, N Kyle

    2011-01-01

    Inappropriate methods are frequently used to calculate the population attributable fraction (AF) for a given exposure of interest. This commonly occurs when authors use adjusted relative risks (RRs) reported in the literature (the "source" data), without access to the original data. In this analysis, we examine the relationship between the direction and magnitude of confounding in the source data and resulting bias in the attributable fraction when incorrect methods are used. We assess confounding by the confounding risk ratio, which is the ratio of the crude RR to the adjusted RR. We assess bias in the AF by the ratio of the incorrectly calculated AF to the correctly calculated AF. Using generated data, we examine the relationship between confounding and AF bias under various scenarios of population prevalence of exposure and strength of the exposure-disease association. For confounding risk ratios greater than 1.0 (ie, crude RR >adjusted RR), the AF is underestimated; for confounding risk ratios less than 1.0 (ie, crude RR Bias in the AF increases as the magnitude of the confounding increases, and is dependent on the prevalence of exposure in the total population, with bias greatest at the lowest prevalence of exposure. Bias in the AF is also higher when the exposure-disease association is weaker. Results of these analyses can assist interpretation of incorrectly calculated attributable fraction estimates commonly reported in the epidemiologic literature.

  8. Investigating bias in squared regression structure coefficients

    PubMed Central

    Nimon, Kim F.; Zientek, Linda R.; Thompson, Bruce

    2015-01-01

    The importance of structure coefficients and analogs of regression weights for analysis within the general linear model (GLM) has been well-documented. The purpose of this study was to investigate bias in squared structure coefficients in the context of multiple regression and to determine if a formula that had been shown to correct for bias in squared Pearson correlation coefficients and coefficients of determination could be used to correct for bias in squared regression structure coefficients. Using data from a Monte Carlo simulation, this study found that squared regression structure coefficients corrected with Pratt's formula produced less biased estimates and might be more accurate and stable estimates of population squared regression structure coefficients than estimates with no such corrections. While our findings are in line with prior literature that identified multicollinearity as a predictor of bias in squared regression structure coefficients but not coefficients of determination, the findings from this study are unique in that the level of predictive power, number of predictors, and sample size were also observed to contribute bias in squared regression structure coefficients. PMID:26217273

  9. RF cavities with transversely biased ferrite tuning

    SciTech Connect

    Smythe, W.R.; Brophy, T.G.; Carlini, R.D.; Friedrichs, C.C.; Grisham, D.L.; Spalek, G.; Wilkerson, L.C.

    1985-10-01

    Earley et al. suggested that ferrite tuned rf cavities have lower ferrite power dissipation if the ferrite bias field is perpendicular rather than parallel to the rf magnetic field. A 50-84 MHz cavity has been constructed in which ferrite can be biased either way. Low power measurements of six microwave ferrites show that the magnetic Q's of these ferrites under perpendicular bias are much higher than under parallel bias, and that the high Q region extends over a much wider range of rf permeability. TDK Y-5 ferrite was found to have a magnetic Q of 10,800, 4,800, 1,200 and 129 at rf permeabilities of 1.2, 2.4, 3.7 and 4.5, respectively. Measurements of perpendicularly biased ferrite at various power levels were made in a coaxial line cavity. The Q of Y-5 ferrite was found to decrease by less than a factor of 2 as the power density in the ferrite was increased to 1.3 W/cmT. A cavity design for a 6 GeV, high current, rapid cycling synchrotron using transversely biased ferrite tuning is described.

  10. Immortal time bias in pharmaco-epidemiology.

    PubMed

    Suissa, Samy

    2008-02-15

    Immortal time is a span of cohort follow-up during which, because of exposure definition, the outcome under study could not occur. Bias from immortal time was first identified in the 1970s in epidemiology in the context of cohort studies of the survival benefit of heart transplantation. It recently resurfaced in pharmaco-epidemiology, with several observational studies reporting that various medications can be extremely effective at reducing morbidity and mortality. These studies, while using different cohort designs, all involved some form of immortal time and the corresponding bias. In this paper, the author describes various cohort study designs leading to this bias, quantifies its magnitude under different survival distributions, and illustrates it by using data from a cohort of lung cancer patients. The author shows that for time-based, event-based, and exposure-based cohort definitions, the bias in the rate ratio resulting from misclassified or excluded immortal time increases proportionately to the duration of immortal time. The bias is more pronounced with a decreasing hazard function for the outcome event, as illustrated with the Weibull distribution compared with a constant hazard from the exponential distribution. In conclusion, observational studies of drug benefit in which computerized databases are used must be designed and analyzed properly to avoid immortal time bias.

  11. Wireless Tech Trends 2010. Trend: smartphones.

    PubMed

    Gamble, Kate Huvane

    2010-02-01

    THE LANDSCAPE: Physician use of handhelds is by no means a new concept. But as the devices--particularly the RIM BlackBerry, Apple iPhone and Google Android--become more sophisticated and more applications become available, the game is changing, quickly. And with so many hospitals upgrading their infrastructures to offer ubiquitous wireless coverage, clinicians are using smartphones in the hospital setting to access online tools such as drug references, and communicate with colleagues. For ClOs, it's a no-brainer--physicians and nurses are already carrying these devices, so why not capitalize on the trend by enabling users to access clinical information and link to patient records. A number of organizations have adopted this thinking and are on the road to enabling EMR access via mobile devices. And while there are certainly sticking points, it's an area that many say is poised for significant growth in the next few years. Many innovative organizations are looking to provide access to electronic records and other clinical data through smartphones. Plans are already being formulated to leverage the devices to facilitate patient handoff and sign-out, as well as to link charge capture with quality measures. Cutting-edge organizations are looking to create actionable information for clinicians through software that can analyze data, track patients'progress, and send out alerts when conditions worsen.

  12. Removing Diurnal Cycle Contamination in Satellite-Derived Tropospheric Temperatures: Understanding Tropical Tropospheric Trend Discrepancies

    NASA Astrophysics Data System (ADS)

    Po-Chedley, S.; Thorsen, T. J.; Fu, Q.

    2014-12-01

    Tropical mid-tropospheric temperature (TMT) time series have been constructed by several independent research teams using satellite microwave sounding unit (MSU) measurements beginning in 1978 and advanced MSU (AMSU) measurements since 1998. Despite careful efforts to homogenize the MSU/AMSU measurements, tropical TMT trends disagree by a factor of three even though each analysis uses the same basic data. Previous studies suggest that the discrepancy in tropical TMT temperature trends is largely caused by differences in both the NOAA-9 warm target factor and diurnal drift corrections used by various teams to homogenize the MSU/AMSU measurements. This work introduces a new observationally-based method for removing biases related to satellite diurnal drift. The method relies on minimizing inter-satellite and inter-node drifts by subtracting out a common diurnal cycle determined via linear regression. It is demonstrated that this method is effective at removing intersatellite biases and biases between the ascending (PM) and descending (AM) node of individual satellites in the TMT time series. After TMT bias correction, the ratio of tropical tropospheric temperature trends relative to surface temperature trends is in accord with the ratio from global climate models. It is shown that bias corrections for diurnal drift based on a climate model produce tropical trends very similar to those from the observationally-based correction, with a trend differences smaller than 0.02 K decade-1. Differences among various TMT datasets are explored further. Tropical trends from this work are comparable to those from the Remote Sensing System (RSS) and NOAA datasets despite small differences. Larger differences between this work and UAH are attributed to differences in the treatment of the NOAA-9 target factor and the UAH diurnal cycle correction.

  13. Interpreting Space-Based Trends in Carbon Monoxide with Multiple Models

    NASA Technical Reports Server (NTRS)

    Strode, Sarah A.; Worden, Helen M.; Damon, Megan; Douglass, Anne R.; Duncan, Bryan N.; Emmons, Louisa K.; Lamarque, Jean-Francois; Manyin, Michael; Oman, Luke D.; Rodriguez, Jose M.; Strahan, Susan E.; Tilmes, Simone

    2016-01-01

    We use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of timedependent emission inventories with observations. We find that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000-2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model-observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. These results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.

  14. Interpreting space-based trends in carbon monoxide with multiple models

    NASA Astrophysics Data System (ADS)

    Strode, Sarah A.; Worden, Helen M.; Damon, Megan; Douglass, Anne R.; Duncan, Bryan N.; Emmons, Louisa K.; Lamarque, Jean-Francois; Manyin, Michael; Oman, Luke D.; Rodriguez, Jose M.; Strahan, Susan E.; Tilmes, Simone

    2016-06-01

    We use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We find that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000-2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model-observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. These results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.

  15. Interpreting space-based trends in carbon monoxide with multiple models

    DOE PAGES

    Strode, Sarah A.; Worden, Helen M.; Damon, Megan; ...

    2016-06-10

    Here, we use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We also found that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000–2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias inmore » CO, after applying MOPITT averaging kernels, contributes to the model–observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. Our results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.« less

  16. Interpreting space-based trends in carbon monoxide with multiple models

    SciTech Connect

    Strode, Sarah A.; Worden, Helen M.; Damon, Megan; Douglass, Anne R.; Duncan, Bryan N.; Emmons, Louisa K.; Lamarque, Jean-Francois; Manyin, Michael; Oman, Luke D.; Rodriguez, Jose M.; Strahan, Susan E.; Tilmes, Simone

    2016-06-10

    Here, we use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We also found that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000–2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model–observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. Our results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.

  17. Interpreting Space-Based Trends in Carbon Monoxide with Multiple Models

    NASA Technical Reports Server (NTRS)

    Strode, Sarah A.; Worden, Helen M.; Damon, Megan; Douglass, Anne R.; Duncan, Bryan N.; Emmons, Louisa K.; Lamarque, Jean-Francois; Manyin, Michael; Oman, Luke D.; Rodriguez, Jose M.; hide

    2016-01-01

    We use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of timedependent emission inventories with observations. We find that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000-2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model-observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. These results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.

  18. Productive trends in India's energy intensive industries

    SciTech Connect

    Roy, J.; Sathaye, J.; Sanstad, A.; Mongia, P.; Schumacher, K.

    1999-07-01

    This paper reports on an analysis of productivity growth and input trends in six energy intensive sectors of the Indian economy, using growth accounting and econometric methods. The econometric work estimates rates and factor price biases of technological change using a translog production model with an explicit relationship defined for technological change. Estimates of own-price responses indicate that raising energy prices would be an effective carbon abatement policy for India. At the same time, the authors results suggest that, as with previous findings on the US economy, such policies in India could have negative long run effects on productivity in these sectors. Inter-input substitution possibilities are relatively weak, so that such policies might have negative short and medium term effects on sectoral growth. The authors study provides information relevant for the analysis of costs and benefits of carbon abatement policies applied to India and thus contributes to the emerging body of modeling and analysis of global climate policy.

  19. Reduced susceptibility to confirmation bias in schizophrenia

    PubMed Central

    Doll, Bradley B.; Waltz, James A.; Cockburn, Jeffrey; Brown, Jaime K.; Frank, Michael J.; Gold, James M.

    2014-01-01

    Patients with schizophrenia (SZ) show cognitive impairments on a wide range of tasks, with clear deficiencies in tasks reliant on prefrontal cortex function and less consistently observed impairments in tasks recruiting the striatum. This study leverages tasks hypothesized to differentially recruit these neural structures to assess relative deficiencies of each. Forty-eight patients and 38 controls completed two reinforcement learning tasks hypothesized to interrogate pre-frontal and striatal functions and their interaction. In each task, participants learned reward discriminations by trial and error and were tested on novel stimulus combinations to assess learned values. In the task putatively assessing fronto-striatal interaction, participants were (inaccurately) instructed that one of the stimuli was valuable. Consistent with prior reports and a model of confirmation bias, this manipulation resulted in overvaluation of the instructed stimulus after its true value had been experienced. Patients showed less susceptibility to this confirmation bias effect than did controls. In the choice bias task hypothesized to more purely assess striatal function, biases in endogenously and exogenously chosen actions were assessed. No group differences were observed. In the subset of participants who showed learning in both tasks, larger group differences were observed in the confirmation bias task than in the choice bias task. In the confirmation bias task, patients also showed impairment in the task conditions with no prior instruction. This deficit was most readily observed on the most deterministic discriminations. Taken together, these results suggest impairments in fronto-striatal interaction in SZ, rather than in striatal function per se. PMID:24481852

  20. Contextual Modulation of Biases in Face Recognition

    PubMed Central

    Felisberti, Fatima Maria; Pavey, Louisa

    2010-01-01

    Background The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. Methodology and Findings Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral) embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174). An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2). Such bias was eliminated or attenuated by making participants explicitly aware of “cooperative”, “cheating” and “neutral/indifferent” behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3). Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4). Conclusion The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context. PMID:20886086

  1. Meta-assessment of bias in science

    PubMed Central

    Fanelli, Daniele; Costas, Rodrigo; Ioannidis, John P. A.

    2017-01-01

    Numerous biases are believed to affect the scientific literature, but their actual prevalence across disciplines is unknown. To gain a comprehensive picture of the potential imprint of bias in science, we probed for the most commonly postulated bias-related patterns and risk factors, in a large random sample of meta-analyses taken from all disciplines. The magnitude of these biases varied widely across fields and was overall relatively small. However, we consistently observed a significant risk of small, early, and highly cited studies to overestimate effects and of studies not published in peer-reviewed journals to underestimate them. We also found at least partial confirmation of previous evidence suggesting that US studies and early studies might report more extreme effects, although these effects were smaller and more heterogeneously distributed across meta-analyses and disciplines. Authors publishing at high rates and receiving many citations were, overall, not at greater risk of bias. However, effect sizes were likely to be overestimated by early-career researchers, those working in small or long-distance collaborations, and those responsible for scientific misconduct, supporting hypotheses that connect bias to situational factors, lack of mutual control, and individual integrity. Some of these patterns and risk factors might have modestly increased in intensity over time, particularly in the social sciences. Our findings suggest that, besides one being routinely cautious that published small, highly-cited, and earlier studies may yield inflated results, the feasibility and costs of interventions to attenuate biases in the literature might need to be discussed on a discipline-specific and topic-specific basis. PMID:28320937

  2. Meta-assessment of bias in science.

    PubMed

    Fanelli, Daniele; Costas, Rodrigo; Ioannidis, John P A

    2017-04-04

    Numerous biases are believed to affect the scientific literature, but their actual prevalence across disciplines is unknown. To gain a comprehensive picture of the potential imprint of bias in science, we probed for the most commonly postulated bias-related patterns and risk factors, in a large random sample of meta-analyses taken from all disciplines. The magnitude of these biases varied widely across fields and was overall relatively small. However, we consistently observed a significant risk of small, early, and highly cited studies to overestimate effects and of studies not published in peer-reviewed journals to underestimate them. We also found at least partial confirmation of previous evidence suggesting that US studies and early studies might report more extreme effects, although these effects were smaller and more heterogeneously distributed across meta-analyses and disciplines. Authors publishing at high rates and receiving many citations were, overall, not at greater risk of bias. However, effect sizes were likely to be overestimated by early-career researchers, those working in small or long-distance collaborations, and those responsible for scientific misconduct, supporting hypotheses that connect bias to situational factors, lack of mutual control, and individual integrity. Some of these patterns and risk factors might have modestly increased in intensity over time, particularly in the social sciences. Our findings suggest that, besides one being routinely cautious that published small, highly-cited, and earlier studies may yield inflated results, the feasibility and costs of interventions to attenuate biases in the literature might need to be discussed on a discipline-specific and topic-specific basis.

  3. Future Trends in Children's Web Pages: Probing Hidden Biases for Information Quality

    ERIC Educational Resources Information Center

    Kurubacak, Gulsun

    2007-01-01

    As global digital communication continues to flourish, Children's Web pages become more critical for children to realize not only the surface but also breadth and deeper meanings in presenting these milieus. These pages not only are very diverse and complex but also enable intense communication across social, cultural and political restrictions…

  4. Future Trends in Chlldren's Web Pages: Probing Hidden Biases for Information Quality

    ERIC Educational Resources Information Center

    Kurubacak, Gulsun

    2007-01-01

    As global digital communication continues to flourish, Children's Web pages become more critical for children to realize not only the surface but also breadth and deeper meanings in presenting these milieus. These pages not only are very diverse and complex but also enable intense communication across social, cultural and political restrictions…

  5. Future Trends in Chlldren's Web Pages: Probing Hidden Biases for Information Quality

    ERIC Educational Resources Information Center

    Kurubacak, Gulsun

    2007-01-01

    As global digital communication continues to flourish, Children's Web pages become more critical for children to realize not only the surface but also breadth and deeper meanings in presenting these milieus. These pages not only are very diverse and complex but also enable intense communication across social, cultural and political restrictions…

  6. Evaluation and bias correction of Precipitation and Temperature of NARCCAP Regional Climate Models over the North Carolina, US

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Band, L. E.

    2011-12-01

    In this study, five GCM (General Circulation Models)-RCM (Regional Climate Model) combinations from NARCCAP, with both current and future time simulations, are selected for model evaluation bias correction: GFDL-RCM3, CGCM3-RCM3, CGCM3-CRCM, CCSM-CRCM and CCSM-WRFG. Also for model evaluation and bias correction, NARCCAP grids with more than three observed weather stations are available are sampled in North Carolina area. Roughly 30 grids for precipitation and 15 grids for temperature are evaluated and biased corrected grid by grid in each NARCCAP output. The evaluation period is the whole current time NARCCAP data period, 1971~2000. The calibration and validation periods for model bias correction are 15 years. Uncorrected GCM-RCM outputs are calibrated for a 15 year time period (i.e. 1971~1985) and validated another 15 years (i.e. 1986~2000). Results indicate that the five GCM-RCMs generally do not capture extremely high fall season precipitation, which can be caused by tropical cyclones. Other precipitation seasonal biases show distinct patterns with RCM by RCM. In the RCM3s, spring and winter precipitation are overestimated, whereas the CRCMs do not show significant bias. The CGCM3-RCM3 has the least amount of biases in both warm and cold seasons, and CCSM combinations have the largest amount. In terms of the future precipitation, no significant difference is found between current and future NARCCAP precipitation. In terms of the geographic regional differences, piedmont and coastal areas share similar bias trends; however mountain area shows different characteristics. For temperatures, the significant cold bias in daily maximum temperature (Tmax) is found especially in the cold season. The largest Tmax cold bias in monthly scale is -7°C in January for GFDL-RCM3. Also we found that characteristics of Tmax bias patterns depend on regional climate models. For example, the two RCM3s show cold bias throughout the year, whereas the two CRCMs show cold bias in winter

  7. Bias to negative emotions: a depression state-dependent marker in adolescent major depressive disorder.

    PubMed

    Maalouf, Fadi T; Clark, Luke; Tavitian, Lucy; Sahakian, Barbara J; Brent, David; Phillips, Mary L

    2012-06-30

    The aim of the current research was to examine for the first time the extent to which bias to negative emotions in an inhibitory control paradigm is a state or trait marker in major depressive disorder (MDD) in adolescents. We administered the affective go/no go task which measures the ability to switch attention to or away from positive or negative emotional stimuli to 40 adolescents with MDD (20 in acute episode (MDDa) and 20 in remission (MDDr)) and 17 healthy controls (HC). MDDa were significantly faster on the shift to negative target blocks as compared to shift to positive target blocks while HC and MDDr displayed the opposite pattern as measured by an "emotional bias index" (EBI=latency (shift to negative targets)-latency (shift to positive targets)). There was also a trend for an effect of group on commission errors, suggesting more impulsive responding by MDDa than both MDDr and HC independently of stimulus valence throughout the task. Negative bias was not associated with depression severity or medication status. In conclusion, bias to negative emotional stimuli appears to be present in the acute stage of MDD and absent in remission suggesting that it is a depression state-specific marker of MDD in adolescents. Latency emerges as a better proxy of negative bias than commission errors and accuracy on this inhibitory control task in adolescents with MDD.

  8. The extragalactic Cepheid bias: a new test using the period-luminosity-color relation

    NASA Astrophysics Data System (ADS)

    Paturel, G.; Teerikorpi, P.

    2006-06-01

    We use the Period-Luminosity-Color relation (PLC) for Cepheids to test for the existence of a bias in extragalactic distances derived from the classical Period-Luminosity (PL) relation. We calculate the parameters of the PLC using several galaxies observed with the Hubble Space Telescope and show that this calculation must be conducted with a PLC written in a form where the parameters are independent. The coefficients thus obtained are similar to those derived from theoretical models. Calibrating with a few unbiased galaxies, we apply this PLC to all galaxies of the Hubble Space Telescope Key Program (HSTKP) and compare the distance moduli with those published by the HSTKP team. The new distance moduli are larger (more exactly, the larger the distance the larger the difference), consistent with a bias. Further, the bias trend that is observed is the same previously obtained from two independent methods based either on the local Hubble law or on a theoretical model of the bias. The results are quite stable but when we force the PLC relation closer to the classical PL relation by using unrealistic parameters, the agreement with HSTKP distance moduli is retrieved. This also suggests that the PL relation leads to biased distance moduli. The new distance moduli reduce the scatter in the calibration of the absolute magnitude of supernovae SNIa at their maximum. This may also suggest that the relation between the amplitude at maximum and the decay of the light curve Δ m15 may not be as strong as believed.

  9. Bias and Evolution of the Mutationally Accessible Phenotypic Space in a Developmental System

    PubMed Central

    Braendle, Christian; Baer, Charles F.; Félix, Marie-Anne

    2010-01-01

    Genetic and developmental architecture may bias the mutationally available phenotypic spectrum. Although such asymmetries in the introduction of variation may influence possible evolutionary trajectories, we lack quantitative characterization of biases in mutationally inducible phenotypic variation, their genotype-dependence, and their underlying molecular and developmental causes. Here we quantify the mutationally accessible phenotypic spectrum of the vulval developmental system using mutation accumulation (MA) lines derived from four wild isolates of the nematodes Caenorhabditis elegans and C. briggsae. The results confirm that on average, spontaneous mutations degrade developmental precision, with MA lines showing a low, yet consistently increased, proportion of developmental defects and variants. This result indicates strong purifying selection acting to maintain an invariant vulval phenotype. Both developmental system and genotype significantly bias the spectrum of mutationally inducible phenotypic variants. First, irrespective of genotype, there is a developmental bias, such that certain phenotypic variants are commonly induced by MA, while others are very rarely or never induced. Second, we found that both the degree and spectrum of mutationally accessible phenotypic variation are genotype-dependent. Overall, C. briggsae MA lines exhibited a two-fold higher decline in precision than the C. elegans MA lines. Moreover, the propensity to generate specific developmental variants depended on the genetic background. We show that such genotype-specific developmental biases are likely due to cryptic quantitative variation in activities of underlying molecular cascades. This analysis allowed us to identify the mutationally most sensitive elements of the vulval developmental system, which may indicate axes of potential evolutionary variation. Consistent with this scenario, we found that evolutionary trends in the vulval system concern the phenotypic characters that

  10. Mixed Model Association with Family-Biased Case-Control Ascertainment.

    PubMed

    Hayeck, Tristan J; Loh, Po-Ru; Pollack, Samuela; Gusev, Alexander; Patterson, Nick; Zaitlen, Noah A; Price, Alkes L

    2017-01-05

    Mixed models have become the tool of choice for genetic association studies; however, standard mixed model methods may be poorly calibrated or underpowered under family sampling bias and/or case-control ascertainment. Previously, we introduced a liability threshold-based mixed model association statistic (LTMLM) to address case-control ascertainment in unrelated samples. Here, we consider family-biased case-control ascertainment, where case and control subjects are ascertained non-randomly with respect to family relatedness. Previous work has shown that this type of ascertainment can severely bias heritability estimates; we show here that it also impacts mixed model association statistics. We introduce a family-based association statistic (LT-Fam) that is robust to this problem. Similar to LTMLM, LT-Fam is computed from posterior mean liabilities (PML) under a liability threshold model; however, LT-Fam uses published narrow-sense heritability estimates to avoid the problem of biased heritability estimation, enabling correct calibration. In simulations with family-biased case-control ascertainment, LT-Fam was correctly calibrated (average χ(2) = 1.00-1.02 for null SNPs), whereas the Armitage trend test (ATT), standard mixed model association (MLM), and case-control retrospective association test (CARAT) were mis-calibrated (e.g., average χ(2) = 0.50-1.22 for MLM, 0.89-2.65 for CARAT). LT-Fam also attained higher power than other methods in some settings. In 1,259 type 2 diabetes-affected case subjects and 5,765 control subjects from the CARe cohort, downsampled to induce family-biased ascertainment, LT-Fam was correctly calibrated whereas ATT, MLM, and CARAT were again mis-calibrated. Our results highlight the importance of modeling family sampling bias in case-control datasets with related samples. Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  11. [Recent demographic trends].

    PubMed

    1983-01-01

    A review of demographic trends in Luxembourg in 1982 is presented. A decline in fertility, the first since 1977, is noted, together with an increase in divorce, as well as a negative migration balance for the first time since 1967. Topics covered include natural increase and migration, fertility, marriage and divorce, mortality, adoption, and legislation affecting the family. Special consideration is given to the mortality experience of those who were subjected to compulsory labor during World War II.

  12. Trends in tobacco use.

    PubMed

    Calverley, M J; Seals, R R

    1994-06-01

    The production and use of tobacco have been accepted parts of the American life-style for over 500 years. Tobacco use in the United States has gone through many stages over the years. The present article reviews the trends of tobacco use over the last 100 years and the public health strategies recently initiated to control tobacco use and promote public health. Finally, suggestions regarding the dentist's role in limiting tobacco use and promoting public health are presented.

  13. Trending Cardiovascular Nutrition Controversies.

    PubMed

    Freeman, Andrew M; Morris, Pamela B; Barnard, Neal; Esselstyn, Caldwell B; Ros, Emilio; Agatston, Arthur; Devries, Stephen; O'Keefe, James; Miller, Michael; Ornish, Dean; Williams, Kim; Kris-Etherton, Penny

    2017-03-07

    The potential cardiovascular benefits of several trending foods and dietary patterns are still incompletely understood, and nutritional science continues to evolve. However, in the meantime, a number of controversial dietary patterns, foods, and nutrients have received significant media exposure and are mired by hype. This review addresses some of the more popular foods and dietary patterns that are promoted for cardiovascular health to provide clinicians with accurate information for patient discussions in the clinical setting.

  14. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Fioletov, Vitali; Bishop, Lane; Godin, Sophie; Bojkov, Rumen D.; Kirchhoff, Volker; Chanin, Marie-Lise; Zawodny, Joseph M.; Zerefos, Christos S.; Chu, William

    1991-01-01

    An update of the extensive reviews of the state of knowledge of measured ozone trends published in the Report of the International Ozone Trends Panel is presented. The update contains a review of progress since these reports, including reviewing of the ozone records, in most cases through March 1991. Also included are some new, unpublished reanalyses of these records including a complete reevaluation of 29 stations located in the former Soviet Union. The major new advance in knowledge of the measured ozone trend is the existence of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer (TOMS) and Stratospheric Aerosol and Gas Experiment (SAG) instruments. These confirm many of the findings, originally derived from the Dobson record, concerning northern mid-latitude changes in ozone. We now have results from several instruments, whereas the previously reported changes were dependent on the calibration of a single instrument. This update will compare the ozone records from many different instruments to determine whether or not they provide a consistent picture of the ozone change that has occurred in the atmosphere. The update also briefly considers the problem of stratospheric temperature change. As in previous reports, this problem received significantly less attention, and the report is not nearly as complete. This area needs more attention in the future.

  15. When do children exhibit a "yes" bias?

    PubMed

    Okanda, Mako; Itakura, Shoji

    2010-01-01

    This study investigated whether one hundred and thirty-five 3- to 6-year-old children exhibit a yes bias to various yes-no questions and whether their knowledge status affects the production of a yes bias. Three-year-olds exhibited a yes bias to all yes-no questions such as preference-object and knowledge-object questions pertaining to objects, and knowledge-face questions pertaining to facial expressions. Four-year-olds tended to say "yes" only to knowledge-object questions. Five-year-olds did not show any strong response tendency. Six-year-olds exhibited a nay-saying bias to knowledge-face questions. Also, 3-year-olds could indicate the correct option when asked questions with 2 response options. It suggested that 3-year-olds tended to inappropriately say "yes" to yes-no questions, although they knew the answers to the questions. The mechanism of a yes bias was discussed.

  16. Attentional Bias in Euthymic Bipolar I Disorder

    PubMed Central

    Peckham, Andrew D.; Johnson, Sheri L.; Gotlib, Ian H.

    2015-01-01

    Little is known about the nature of the relation between information-processing biases and affective traits in bipolar disorder. The present study was designed to investigate whether attentional biases are evident in persons diagnosed with bipolar disorder when they are in a positive mood state, and whether biases are related to indices of emotion regulation and to prior history of mood episodes. Ninety adults diagnosed with bipolar I disorder and 81 controls with no lifetime mood disorder underwent a positive mood induction and then completed an emotion face dot-probe task; participants in the bipolar disorder group also completed a self-report measure of responses to positive affect. Attentional bias was not related to a diagnosis of bipolar disorder or to symptom severity. Consistent with hypotheses, analyses within the bipolar group indicated that greater dampening of positive affect related to significantly less attention paid to the positively valenced faces. Discussion focuses on the potential role of affective traits in shaping attentional bias in bipolar disorder. PMID:25757517

  17. Concurrent bias correction in hemodynamic data assimilation.

    PubMed

    Hu, Zhenghui; Liu, Huafeng; Shi, Pengcheng

    2012-10-01

    Low-frequency drift in fMRI datasets can be caused by various sources and are generally not of interest in a conventional task-based fMRI experiment. This feature complicates the assimilation approach that is always under specific assumption on statistics of system uncertainties. In this paper, we present a novel approach to the assimilation of nonlinear hemodynamic system with stochastic biased noise. By treating the drift variation as a random-walk process, the assimilation problem was translated into the identification of a nonlinear system in the presence of time-varying bias. We developed a bias aware unscented Kalman estimator to efficiently handle this problem. In this framework, the estimates of bias-free states and drift are separately carried out in two parallel filters, the optimal estimates of the system states then are corrected from bias-free states with drift estimates. The approach can simultaneously deal with the fMRI responses and drift in an assimilation cycle in an on-line fashion. It makes no assumptions of the structure and statistics of the drift, thereby is particularly suited for fMRI imaging where the formulation of real drift remains difficult to acquire. Experiments with synthetic data and real fMRI data are performed to demonstrate feasibility of our approach and to explore its potential advantages over classic polynomial approach. Moreover, we include the comparison of the variability of observables from the scanner and of normalized signal used in assimilation procedure in Appendix.

  18. Random walk with chaotically driven bias

    NASA Astrophysics Data System (ADS)

    Kim, Song-Ju; Naruse, Makoto; Aono, Masashi; Hori, Hirokazu; Akimoto, Takuma

    2016-12-01

    We investigate two types of random walks with a fluctuating probability (bias) in which the random walker jumps to the right. One is a ‘time-quenched framework’ using bias time series such as periodic, quasi-periodic, and chaotic time series (chaotically driven bias). The other is a ‘time-annealed framework’ using the fluctuating bias generated by a stochastic process, which is not quenched in time. We show that the diffusive properties in the time-quenched framework can be characterised by the ensemble average of the time-averaged variance (ETVAR), whereas the ensemble average of the time-averaged mean square displacement (ETMSD) fails to capture the diffusion, even when the total bias is zero. We demonstrate that the ETVAR increases linearly with time, and the diffusion coefficient can be estimated by the time average of the local diffusion coefficient. In the time-annealed framework, we analytically and numerically show normal diffusion and superdiffusion, similar to the Lévy walk. Our findings will lead to new developments in information and communication technologies, such as efficient energy transfer for information propagation and quick solution searching.

  19. Random walk with chaotically driven bias.

    PubMed

    Kim, Song-Ju; Naruse, Makoto; Aono, Masashi; Hori, Hirokazu; Akimoto, Takuma

    2016-12-08

    We investigate two types of random walks with a fluctuating probability (bias) in which the random walker jumps to the right. One is a 'time-quenched framework' using bias time series such as periodic, quasi-periodic, and chaotic time series (chaotically driven bias). The other is a 'time-annealed framework' using the fluctuating bias generated by a stochastic process, which is not quenched in time. We show that the diffusive properties in the time-quenched framework can be characterised by the ensemble average of the time-averaged variance (ETVAR), whereas the ensemble average of the time-averaged mean square displacement (ETMSD) fails to capture the diffusion, even when the total bias is zero. We demonstrate that the ETVAR increases linearly with time, and the diffusion coefficient can be estimated by the time average of the local diffusion coefficient. In the time-annealed framework, we analytically and numerically show normal diffusion and superdiffusion, similar to the Lévy walk. Our findings will lead to new developments in information and communication technologies, such as efficient energy transfer for information propagation and quick solution searching.

  20. Graphene nanoribbon devices at high bias.

    PubMed

    Han, Melinda Y; Kim, Philip

    2014-01-01

    We present the electron transport in graphene nanoribbons (GNRs) at high electric bias conduction. When graphene is patterned into a few tens of nanometer width of a ribbon shape, the carriers are confined to a quasi-one-dimensional (1D) system. Combining with the disorders in the system, this quantum confinement can lead into a transport gap in the energy spectrum of the GNRs. Similar to CNTs, this gap depends on the width of the GNR. In this review, we examine the electronic properties of lithographically fabricated GNRs, focusing on the high bias transport characteristics of GNRs as a function of density tuned by a gate voltage. We investigate the transport behavior of devices biased up to a few volts, a regime more relevant for electronics applications. We find that the high bias transport behavior in this limit can be described by hot electron scattered by the surface phonon emission, leading to a carrier velocity saturation. We also showed an enhanced current saturation effect in the GNRs with an efficient gate coupling. This effect results from the introduction of the charge neutrality point into the channel, and is similar to pinch-off in MOSFET devices. We also observe that heating effects in graphene at high bias are significant.

  1. Graphene nanoribbon devices at high bias

    NASA Astrophysics Data System (ADS)

    Han, Melinda Y.; Kim, Philip

    2014-02-01

    We present the electron transport in graphene nanoribbons (GNRs) at high electric bias conduction. When graphene is patterned into a few tens of nanometer width of a ribbon shape, the carriers are confined to a quasi-one-dimensional (1D) system. Combining with the disorders in the system, this quantum confinement can lead into a transport gap in the energy spectrum of the GNRs. Similar to CNTs, this gap depends on the width of the GNR. In this review, we examine the electronic properties of lithographically fabricated GNRs, focusing on the high bias transport characteristics of GNRs as a function of density tuned by a gate voltage. We investigate the transport behavior of devices biased up to a few volts, a regime more relevant for electronics applications. We find that the high bias transport behavior in this limit can be described by hot electron scattered by the surface phonon emission, leading to a carrier velocity saturation. We also showed an enhanced current saturation effect in the GNRs with an efficient gate coupling. This effect results from the introduction of the charge neutrality point into the channel, and is similar to pinch-off in MOSFET devices. We also observe that heating effects in graphene at high bias are significant.

  2. Non-Gaussian halo assembly bias

    SciTech Connect

    Reid, Beth A.; Verde, Licia; Dolag, Klaus; Matarrese, Sabino; Moscardini, Lauro E-mail: liciaverde@icc.ub.edu E-mail: sabino.matarrese@pd.infn.it

    2010-07-01

    The strong dependence of the large-scale dark matter halo bias on the (local) non-Gaussianity parameter, f{sub NL}, offers a promising avenue towards constraining primordial non-Gaussianity with large-scale structure surveys. In this paper, we present the first detection of the dependence of the non-Gaussian halo bias on halo formation history using N-body simulations. We also present an analytic derivation of the expected signal based on the extended Press-Schechter formalism. In excellent agreement with our analytic prediction, we find that the halo formation history-dependent contribution to the non-Gaussian halo bias (which we call non-Gaussian halo assembly bias) can be factorized in a form approximately independent of redshift and halo mass. The correction to the non-Gaussian halo bias due to the halo formation history can be as large as 100%, with a suppression of the signal for recently formed halos and enhancement for old halos. This could in principle be a problem for realistic galaxy surveys if observational selection effects were to pick galaxies occupying only recently formed halos. Current semi-analytic galaxy formation models, for example, imply an enhancement in the expected signal of ∼ 23% and ∼ 48% for galaxies at z = 1 selected by stellar mass and star formation rate, respectively.

  3. Bias in Markov models of disease.

    PubMed

    Faissol, Daniel M; Griffin, Paul M; Swann, Julie L

    2009-08-01

    We examine bias in Markov models of diseases, including both chronic and infectious diseases. We consider two common types of Markov disease models: ones where disease progression changes by severity of disease, and ones where progression of disease changes in time or by age. We find sufficient conditions for bias to exist in models with aggregated transition probabilities when compared to models with state/time dependent transition probabilities. We also find that when aggregating data to compute transition probabilities, bias increases with the degree of data aggregation. We illustrate by examining bias in Markov models of Hepatitis C, Alzheimer's disease, and lung cancer using medical data and find that the bias is significant depending on the method used to aggregate the data. A key implication is that by not incorporating state/time dependent transition probabilities, studies that use Markov models of diseases may be significantly overestimating or underestimating disease progression. This could potentially result in incorrect recommendations from cost-effectiveness studies and incorrect disease burden forecasts.

  4. Random walk with chaotically driven bias

    PubMed Central

    Kim, Song-Ju; Naruse, Makoto; Aono, Masashi; Hori, Hirokazu; Akimoto, Takuma

    2016-01-01

    We investigate two types of random walks with a fluctuating probability (bias) in which the random walker jumps to the right. One is a ‘time-quenched framework’ using bias time series such as periodic, quasi-periodic, and chaotic time series (chaotically driven bias). The other is a ‘time-annealed framework’ using the fluctuating bias generated by a stochastic process, which is not quenched in time. We show that the diffusive properties in the time-quenched framework can be characterised by the ensemble average of the time-averaged variance (ETVAR), whereas the ensemble average of the time-averaged mean square displacement (ETMSD) fails to capture the diffusion, even when the total bias is zero. We demonstrate that the ETVAR increases linearly with time, and the diffusion coefficient can be estimated by the time average of the local diffusion coefficient. In the time-annealed framework, we analytically and numerically show normal diffusion and superdiffusion, similar to the Lévy walk. Our findings will lead to new developments in information and communication technologies, such as efficient energy transfer for information propagation and quick solution searching. PMID:27929091

  5. Who’s afraid of response bias?

    PubMed Central

    Peters, Megan A. K.; Ro, Tony; Lau, Hakwan

    2016-01-01

    Response bias (or criterion) contamination is insidious in studies of consciousness: that observers report they do not see a stimulus may not mean they have absolutely no subjective experience; they may be giving such reports in relative terms in the context of other stimuli. Bias-free signal detection theoretic measures provide an excellent method for avoiding response bias confounds, and many researchers correctly adopt this approach. However, here we discuss how a fixation on avoiding criterion effects can also be misleading and detrimental to fruitful inquiry. In a recent paper, Balsdon and Azzopardi (Absolute and relative blindsight. Consciousness and Cognition 2015; 32:79–91.) claimed that contamination by response bias led to flawed findings in a previous report of “relative blindsight”. We argue that their criticisms are unfounded. They mistakenly assumed that others were trying (and failing) to apply their preferred methods to remove bias, when there was no such intention. They also dismissed meaningful findings because of their dependence on criterion, but such dismissal is problematic: many real effects necessarily depend on criterion. Unfortunately, these issues are technically tedious, and we discuss how they may have confused others to misapply psychophysical metrics and to draw questionable conclusions about the nature of TMS (transcranial magnetic stimulation)-induced blindsight. We conclude by discussing the conceptual importance of criterion effects in studies of conscious awareness: we need to treat them carefully, but not to avoid them without thinking. PMID:27499928

  6. Estimation of river and stream temperature trends under haphazard sampling

    USGS Publications Warehouse

    Gray, Brian R.; Lyubchich, Vyacheslav; Gel, Yulia R.; Rogala, James T.; Robertson, Dale M.; Wei, Xiaoqiao

    2015-01-01

    Long-term temporal trends in water temperature in rivers and streams are typically estimated under the assumption of evenly-spaced space-time measurements. However, sampling times and dates associated with historical water temperature datasets and some sampling designs may be haphazard. As a result, trends in temperature may be confounded with trends in time or space of sampling which, in turn, may yield biased trend estimators and thus unreliable conclusions. We address this concern using multilevel (hierarchical) linear models, where time effects are allowed to vary randomly by day and date effects by year. We evaluate the proposed approach by Monte Carlo simulations with imbalance, sparse data and confounding by trend in time and date of sampling. Simulation results indicate unbiased trend estimators while results from a case study of temperature data from the Illinois River, USA conform to river thermal assumptions. We also propose a new nonparametric bootstrap inference on multilevel models that allows for a relatively flexible and distribution-free quantification of uncertainties. The proposed multilevel modeling approach may be elaborated to accommodate nonlinearities within days and years when sampling times or dates typically span temperature extremes.

  7. Guidelines for the Creative Use of Biased Materials in a Non-Biased Way.

    ERIC Educational Resources Information Center

    Women on Words and Images, Princeton, NJ.

    Intended to aid vocational education teachers in recognizing and dealing with sex biases contained in classroom materials, guidelines are offered to help the teacher deal with sexist language, roles, portrayal of personal traits, and illustrations. It is suggested, for example, that teachers point out sex-biased statements and discuss with…

  8. Biased diffusion in tubes of alternating diameter: Numerical study over a wide range of biasing force

    SciTech Connect

    Makhnovskii, Yurii A.; Berezhkovskii, Alexander M.; Antipov, Anatoly E.; Zitserman, Vladimir Yu.

    2015-11-07

    This paper is devoted to particle transport in a tube formed by alternating wide and narrow sections, in the presence of an external biasing force. The focus is on the effective transport coefficients—mobility and diffusivity, as functions of the biasing force and the geometric parameters of the tube. Dependences of the effective mobility and diffusivity on the tube geometric parameters are known in the limiting cases of no bias and strong bias. The approximations used to obtain these results are inapplicable at intermediate values of the biasing force. To bridge the two limits Brownian dynamics simulations were run to determine the transport coefficients at intermediate values of the force. The simulations were performed for a representative set of tube geometries over a wide range of the biasing force. They revealed that there is a range of the narrow section length, where the force dependence of the mobility has a maximum. In contrast, the diffusivity is a monotonically increasing function of the force. A simple formula is proposed, which reduces to the known dependences of the diffusivity on the tube geometric parameters in both limits of zero and strong bias. At intermediate values of the biasing force, the formula catches the diffusivity dependence on the narrow section length, if the radius of these sections is not too small.

  9. Biased diffusion in tubes of alternating diameter: Numerical study over a wide range of biasing force.

    PubMed

    Makhnovskii, Yurii A; Berezhkovskii, Alexander M; Antipov, Anatoly E; Zitserman, Vladimir Yu

    2015-11-07

    This paper is devoted to particle transport in a tube formed by alternating wide and narrow sections, in the presence of an external biasing force. The focus is on the effective transport coefficients--mobility and diffusivity, as functions of the biasing force and the geometric parameters of the tube. Dependences of the effective mobility and diffusivity on the tube geometric parameters are known in the limiting cases of no bias and strong bias. The approximations used to obtain these results are inapplicable at intermediate values of the biasing force. To bridge the two limits Brownian dynamics simulations were run to determine the transport coefficients at intermediate values of the force. The simulations were performed for a representative set of tube geometries over a wide range of the biasing force. They revealed that there is a range of the narrow section length, where the force dependence of the mobility has a maximum. In contrast, the diffusivity is a monotonically increasing function of the force. A simple formula is proposed, which reduces to the known dependences of the diffusivity on the tube geometric parameters in both limits of zero and strong bias. At intermediate values of the biasing force, the formula catches the diffusivity dependence on the narrow section length, if the radius of these sections is not too small.

  10. Auto Bias Control technique for optical 16-QAM transmitter with asymmetric bias dithering.

    PubMed

    Kawakami, Hiroto; Kobayashi, Takayuki; Yoshida, Eiji; Miyamoto, Yutaka

    2011-12-12

    ABC (Auto Bias Control) technique for QAM (Quadrature Amplitude Modulation) transmitter is demonstrated. 16-QAM (10G baud) is generated and controlled using a single IQ modulator and asymmetric bias dithering technique. Measured penalty is 0.3 dB.

  11. Expectancy biases in fear and anxiety and their link to biases in attention.

    PubMed

    Aue, Tatjana; Okon-Singer, Hadas

    2015-12-01

    Healthy individuals often exhibit prioritized processing of aversive information, as manifested in enhanced orientation of attention to threatening stimuli compared with neutral items. In contrast to this adaptive behavior, anxious, fearful, and phobic individuals show exaggerated attention biases to threat. In addition, they overestimate the likelihood of encountering their feared stimulus and the severity of the consequences; both are examples of expectancy biases. The co-occurrence of attention and expectancy biases in fear and anxiety raises the question about causal influences. Herein, we summarize findings related to expectancy biases in fear and anxiety, and their association with attention biases. We suggest that evidence calls for more comprehensive research strategies in the investigation of mutual influences between expectancy and attention biases, as well as their combined effects on fear and anxiety. Moreover, both types of bias need to be related to other types of distorted information processing commonly observed in fear and anxiety (e.g., memory and interpretation biases). Finally, we propose new research directions that may be worth considering in developing more effective treatments for anxiety disorders.

  12. Attention bias modification training under working memory load increases the magnitude of change in attentional bias.

    PubMed

    Clarke, Patrick J F; Branson, Sonya; Chen, Nigel T M; Van Bockstaele, Bram; Salemink, Elske; MacLeod, Colin; Notebaert, Lies

    2017-12-01

    Attention bias modification (ABM) procedures have shown promise as a therapeutic intervention, however current ABM procedures have proven inconsistent in their ability to reliably achieve the requisite change in attentional bias needed to produce emotional benefits. This highlights the need to better understand the precise task conditions that facilitate the intended change in attention bias in order to realise the therapeutic potential of ABM procedures. Based on the observation that change in attentional bias occurs largely outside conscious awareness, the aim of the current study was to determine if an ABM procedure delivered under conditions likely to preclude explicit awareness of the experimental contingency, via the addition of a working memory load, would contribute to greater change in attentional bias. Bias change was assessed among 122 participants in response to one of four ABM tasks given by the two experimental factors of ABM training procedure delivered either with or without working memory load, and training direction of either attend-negative or avoid-negative. Findings revealed that avoid-negative ABM procedure under working memory load resulted in significantly greater reductions in attentional bias compared to the equivalent no-load condition. The current findings will require replication with clinical samples to determine the utility of the current task for achieving emotional benefits. These present findings are consistent with the position that the addition of a working memory load may facilitate change in attentional bias in response to an ABM training procedure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Cognitive Bias Modification Training in Adolescents: Effects on Interpretation Biases and Mood

    ERIC Educational Resources Information Center

    Lothmann, Claudia; Holmes, Emily A.; Chan, Stella W. Y.; Lau, Jennifer Y. F.

    2011-01-01

    Background: Negative biases in the interpretation of ambiguous material have been linked to anxiety and mood problems. Accumulating data from adults show that positive and negative interpretation styles can be induced through cognitive bias modification (CBM) paradigms with accompanying changes in mood. Despite the therapeutic potential of…

  14. Piezoelectric tuning of exchange bias from negative to positive bias fields

    NASA Astrophysics Data System (ADS)

    Polisetty, Srinivas; Binek, Christian; Sahoo, Sarbeswar

    2010-03-01

    Tuning of the exchange bias has been attempted using magnetoelectric and multiferroic systems. Alternatively, we propose tuning of the exchange bias via the piezoelectric property of ferroelectric material. A ferromagnetic Co thin film is deposited on top of a ferroelectric tetragonal BaTiO3 (001) by using MBE at a base pressure of 1.5x10^10 m bar. An ex-situ antiferromagnetic CoO film is naturally formed on top of the Co Hereby, the piezoelectric BaTiO3 induced electrically tunable stress in the adjacent Co film. The stress induced strain alters the magnetic anisotropy of the Co film and by that the magnetization at the Co/CoO-interface modifying the exchange bias field. This includes sign change of the exchange bias from negative to positive bias fields by increasing electric field applied on BaTiO3. The observed complex electric field dependence of the exchange bias is interpreted through competition between ferromagnetic and antiferromagnetic exchange at the rough Co/CoO interface. The competition involves weakening of negative exchange bias through deviations from collineraity of the Co and CoO interface magnetization and simultaneous activation of antiferromagnetic exchange giving rise to a crossover into positive exchange bias.

  15. Bias analysis applied to Agricultural Health Study publications to estimate non-random sources of uncertainty

    PubMed Central

    Lash, Timothy L

    2007-01-01

    Background The associations of pesticide exposure with disease outcomes are estimated without the benefit of a randomized design. For this reason and others, these studies are susceptible to systematic errors. I analyzed studies of the associations between alachlor and glyphosate exposure and cancer incidence, both derived from the Agricultural Health Study cohort, to quantify the bias and uncertainty potentially attributable to systematic error. Methods For each study, I identified the prominent result and important sources of systematic error that might affect it. I assigned probability distributions to the bias parameters that allow quantification of the bias, drew a value at random from each assigned distribution, and calculated the estimate of effect adjusted for the biases. By repeating the draw and adjustment process over multiple iterations, I generated a frequency distribution of adjusted results, from which I obtained a point estimate and simulation interval. These methods were applied without access to the primary record-level dataset. Results The conventional estimates of effect associating alachlor and glyphosate exposure with cancer incidence were likely biased away from the null and understated the uncertainty by quantifying only random error. For example, the conventional p-value for a test of trend in the alachlor study equaled 0.02, whereas fewer than 20% of the bias analysis iterations yielded a p-value of 0.02 or lower. Similarly, the conventional fully-adjusted result associating glyphosate exposure with multiple myleoma equaled 2.6 with 95% confidence interval of 0.7 to 9.4. The frequency distribution generated by the bias analysis yielded a median hazard ratio equal to 1.5 with 95% simulation interval of 0.4 to 8.9, which was 66% wider than the conventional interval. Conclusion Bias analysis provides a more complete picture of true uncertainty than conventional frequentist statistical analysis accompanied by a qualitative description of study

  16. The impact of historical biases on the XBT-derived meridional overturning circulation estimates at 34°S

    NASA Astrophysics Data System (ADS)

    Goes, Marlos; Baringer, Molly; Goni, Gustavo

    2015-03-01

    An observational system based on high-density expendable bathythermograph (XBT) data has provided the longest record of the South Atlantic meridional overturning and heat transport estimates across 34°S. Measurement biases are a point of concern for the capability of an XBT system to capture long-term trends in volume and heat transports, and the impact of such biases on the meridional overturning estimates has never been quantified. In the present study, the sensitivity of the meridional overturning circulation and heat transport to uncertainties in XBT measurements is quantified under the framework of an eddy-resolving model simulation. Results show that XBT measurement biases after 2010 can translate into small meridional overturning errors on the order of 3% or 0.38 Sv (1Sv = 106 m3 s-1), and 0.025 PW (1 PW = 1015 W) or 8% of the meridional heat transport in the model. Historical XBT-derived trends in transport estimates across 34°S are stronger and statistically significant after the late 1990s, 0.3 Sv decade-1 and 0.02 PW decade-1. These trends are mostly due to the XBT linear depth bias, with smaller contributions associated with temperature and depth offsets from the historical record. Long-term trends calculated from Simple Ocean Data Assimilation reanalysis, estimated as 0.1 Sv/decade and 0.006 PW/decade, are 3 times smaller than the XBT-derived historical trends. Therefore, an adequate correction of historical XBT data is necessary for an early detection of trends in the meridional overturning circulation and heat transport.

  17. Screen bias detection and statistical minimisation from Western Mediterranean long temperature records

    NASA Astrophysics Data System (ADS)

    Brunet, M.; Asín, J.; Sigró, J.; Bañon, M.; García, F.; Aguilar, E.; Palenzuela, J. E.; Jones, P. D.

    2009-04-01

    The substitution of ancient shelters by modern Stevenson screens is thought to be the main cause of breaking homogeneity of long temperature records. It is also known that the so-called screen bias has induced a warm (cold) bias in long maximum (minimum) temperature records, whose magnitude is dependent on the latitude, on the moment of the year / day or on the meteorological conditions of the measurement (Parker, 1994). In the Mediterranean region, screen change is responsible for a strong positive bias in daily maximum temperature records (of about 1 °C at the annual scale, which shows a clear annual cycle with higher values in summer and lower in winter), meanwhile daily minimum temperatures show a small cold bias (about 0.2 °C, without seasonal differential behaviour) compared to the modern observations (e. g. Nichols et al., 1996; Brunet et al., 2008). Therefore, the use of the uncorrected data in assessments of long-term temperature variability and change will give negatively-biased results in term of trends, largely underestimating (slightly overestimating) maximum (minimum) long-term rate of temperature change, respectively; this bias would affect so to trend's estimation of the derived daily mean and diurnal temperature range series. Here we present an exploratory statistical analysis aimed at the minimisation of the "screen bias" from the affected Western Mediterranean air temperature time series. Our approach lies in the statistical analysis of about 6 years (5 years as calibration and 1 year as validation periods) of daily paired maximum and minimum temperature observations taken under a replicated ancient MONTSOURI shelter (one of the open stands used in the past to protect thermometers from direct or indirect radiation and wetting) and the modern STEVENSON screen installed in two experimental sites, the meteorological gardens of La Coruña and Murcia, Spain. These sites are representing the 2 most contrasted Mediterranean climate types: Oceanic

  18. Gregorian calendar bias in monthly temperature databases

    NASA Astrophysics Data System (ADS)

    Cerveny, Randall S.; Svoma, Bohumil M.; Balling, Robert C.; Vose, Russell S.

    2008-10-01

    In this study we address a systematic bias in climate records that manifests due to the establishment of the Gregorian calendar system and exerts a statistically significant effect on monthly and seasonal temperature records. The addition of one extra day in February normally every fourth year produces a significant seasonal drift in the monthly values of that year in four major temperature datasets used in climate change analysis. The addition of a `leap year day' for the Northern Hemisphere creates statistically significantly colder months of July to December and, to a lesser degree warmer months of February to June than correspondingly common (non-leap year) months. The discovery of such a fundamental bias in four major temperature datasets used in climate analysis (and likely present in any dataset displaying strong annual cycles, e.g., U.S. streamflow data) indicates the continued need for detailed scrutiny of climate records for such biases.

  19. Sex-biased dispersal of human ancestors.

    PubMed

    Sugiyama, Yukimaru

    2017-07-01

    Some anthropologists and primatologists have argued that, judging by extant chimpanzees and humans, which are female-biased dispersers, the common ancestors of humans and chimpanzees were also female-biased dispersers. It has been thought that sex-biased dispersal patterns have been genetically transmitted for millions of years. However, this character has changed many times with changes in environment and life-form during human evolution and historical times. I examined life-form and social organization of nonhuman primates, among them gatherers (foragers), hunter-gatherers, agriculturalists, industrialists, and modern and extant humans. I conclude that dispersal patterns changed in response to environmental conditions during primate and human evolution. © 2017 Wiley Periodicals, Inc.

  20. Optimism Bias in Fans and Sports Reporters.

    PubMed

    Love, Bradley C; Kopeć, Łukasz; Guest, Olivia

    2015-01-01

    People are optimistic about their prospects relative to others. However, existing studies can be difficult to interpret because outcomes are not zero-sum. For example, one person avoiding cancer does not necessitate that another person develops cancer. Ideally, optimism bias would be evaluated within a closed formal system to establish with certainty the extent of the bias and the associated environmental factors, such that optimism bias is demonstrated when a population is internally inconsistent. Accordingly, we asked NFL fans to predict how many games teams they liked and disliked would win in the 2015 season. Fans, like ESPN reporters assigned to cover a team, were overly optimistic about their team's prospects. The opposite pattern was found for teams that fans disliked. Optimism may flourish because year-to-year team results are marked by auto-correlation and regression to the group mean (i.e., good teams stay good, but bad teams improve).

  1. Optimism Bias in Fans and Sports Reporters

    PubMed Central

    Love, Bradley C.

    2015-01-01

    People are optimistic about their prospects relative to others. However, existing studies can be difficult to interpret because outcomes are not zero-sum. For example, one person avoiding cancer does not necessitate that another person develops cancer. Ideally, optimism bias would be evaluated within a closed formal system to establish with certainty the extent of the bias and the associated environmental factors, such that optimism bias is demonstrated when a population is internally inconsistent. Accordingly, we asked NFL fans to predict how many games teams they liked and disliked would win in the 2015 season. Fans, like ESPN reporters assigned to cover a team, were overly optimistic about their team’s prospects. The opposite pattern was found for teams that fans disliked. Optimism may flourish because year-to-year team results are marked by auto-correlation and regression to the group mean (i.e., good teams stay good, but bad teams improve). PMID:26352146

  2. Racial Bias in Perceptions of Others’ Pain

    PubMed Central

    Trawalter, Sophie; Hoffman, Kelly M.; Waytz, Adam

    2012-01-01

    The present work provides evidence that people assume a priori that Blacks feel less pain than do Whites. It also demonstrates that this bias is rooted in perceptions of status and the privilege (or hardship) status confers, not race per se. Archival data from the National Football League injury reports reveal that, relative to injured White players, injured Black players are deemed more likely to play in a subsequent game, possibly because people assume they feel less pain. Experiments 1–4 show that White and Black Americans–including registered nurses and nursing students–assume that Black people feel less pain than do White people. Finally, Experiments 5 and 6 provide evidence that this bias is rooted in perceptions of status, not race per se. Taken together, these data have important implications for understanding race-related biases and healthcare disparities. PMID:23155390

  3. Recursive bias estimation for high dimensional smoothers

    SciTech Connect

    Hengartner, Nicolas W; Matzner-lober, Eric; Cornillon, Pierre - Andre

    2008-01-01

    In multivariate nonparametric analysis, sparseness of the covariates also called curse of dimensionality, forces one to use large smoothing parameters. This leads to biased smoothers. Instead of focusing on optimally selecting the smoothing parameter, we fix it to some reasonably large value to ensure an over-smoothing of the data. The resulting smoother has a small variance but a substantial bias. In this paper, we propose to iteratively correct the bias initial estimator by an estimate of the latter obtained by smoothing the residuals. We examine in detail the convergence of the iterated procedure for classical smoothers and relate our procedure to L{sub 2}-Boosting. We apply our method to simulated and real data and show that our method compares favorably with existing procedures.

  4. Optimizing biased semiconductor superlattices for terahertz amplification

    SciTech Connect

    Lei, Xiaoli; Wang, Dawei; Wu, Zhaoxin; Dignam, M. M.

    2014-08-11

    Over the past 15 yr or more, researchers have been trying to achieve gain for electromagnetic fields in the terahertz frequency region using biased semiconductor superlattices, but with little success. In this work, we employ our model of the excitonic states in biased GaAs/Al{sub 0.3}Ga{sub 0.7}As semiconductor superlattices to find the optimal structures for amplification of terahertz radiation. In particular, we determine the optimum well width, barrier width, and bias field for terahertz fields with frequencies ranging from 1 to 4 terahertz. We find that gain coefficients on the order of 40 cm{sup −1} should be achievable over most of this frequency range.

  5. Racial bias in perceptions of others' pain.

    PubMed

    Trawalter, Sophie; Hoffman, Kelly M; Waytz, Adam

    2012-01-01

    The present work provides evidence that people assume a priori that Blacks feel less pain than do Whites. It also demonstrates that this bias is rooted in perceptions of status and the privilege (or hardship) status confers, not race per se. Archival data from the National Football League injury reports reveal that, relative to injured White players, injured Black players are deemed more likely to play in a subsequent game, possibly because people assume they feel less pain. Experiments 1-4 show that White and Black Americans-including registered nurses and nursing students-assume that Black people feel less pain than do White people. Finally, Experiments 5 and 6 provide evidence that this bias is rooted in perceptions of status, not race per se. Taken together, these data have important implications for understanding race-related biases and healthcare disparities.

  6. Tunable bands in biased multilayer epitaxial graphene.

    PubMed

    Williams, Michael D; Samarakoon, Duminda K; Hess, Dennis W; Wang, Xiao-Qian

    2012-04-28

    We have studied the electronic characteristics of multilayer epitaxial graphene under a perpendicularly applied electric bias. Ultraviolet photoemission spectroscopy measurements reveal that there is notable variation of the electronic density-of-states in valence bands near the Fermi level. Evolution of the electronic structure of graphite and rotational-stacked multilayer epitaxial graphene as a function of the applied electric bias is investigated using first-principles density-functional theory including interlayer van der Waals interactions. The experimental and theoretical results demonstrate that the tailoring of electronic band structure correlates with the interlayer coupling tuned by the applied bias. The implications of controllable electronic structure of rotationally fault-stacked epitaxial graphene grown on the C-face of SiC for future device applications are discussed.

  7. Perceptual bias for forward-facing motion

    NASA Technical Reports Server (NTRS)

    Mcbeath, Michael K.; Morikawa, Kazunori; Kaiser, Mary K.

    1992-01-01

    When an occluded horizontal row of shapes is shifted laterally, apparent motion can be experienced in either the leftward or the rightward direction. Four experiments provide evidence for a motion bias in the direction that shapes appear to face. The bias tended to be largest when directionality was specified geometrically (e.g., triangles), next largest when it was specified biologically (e.g., mice), and absent when it was specified calligraphically (e.g., letter R). The bias increased parametrically as a function of triangle pointedness and was consistent with the directional interpretation of an ambiguous duck-rabbit. The results support the existence of a cognitively specified forward-facing attribute that can influence experienced direction of motion.

  8. Perceptual bias for forward-facing motion

    NASA Technical Reports Server (NTRS)

    Mcbeath, Michael K.; Morikawa, Kazunori; Kaiser, Mary K.

    1992-01-01

    When an occluded horizontal row of shapes is shifted laterally, apparent motion can be experienced in either the leftward or the rightward direction. Four experiments provide evidence for a motion bias in the direction that shapes appear to face. The bias tended to be largest when directionality was specified geometrically (e.g., triangles), next largest when it was specified biologically (e.g., mice), and absent when it was specified calligraphically (e.g., letter R). The bias increased parametrically as a function of triangle pointedness and was consistent with the directional interpretation of an ambiguous duck-rabbit. The results support the existence of a cognitively specified forward-facing attribute that can influence experienced direction of motion.

  9. Motion, identity and the bias toward agency

    PubMed Central

    Fields, Chris

    2014-01-01

    The well-documented human bias toward agency as a cause and therefore an explanation of observed events is typically attributed to evolutionary selection for a “social brain”. Based on a review of developmental and adult behavioral and neurocognitive data, it is argued that the bias toward agency is a result of the default human solution, developed during infancy, to the computational requirements of object re-identification over gaps in observation of more than a few seconds. If this model is correct, overriding the bias toward agency to construct mechanistic explanations of observed events requires structure-mapping inferences, implemented by the pre-motor action planning system, that replace agents with mechanisms as causes of unobserved changes in contextual or featural properties of objects. Experiments that would test this model are discussed. PMID:25191245

  10. Learning biases predict a word order universal.

    PubMed

    Culbertson, Jennifer; Smolensky, Paul; Legendre, Géraldine

    2012-03-01

    How recurrent typological patterns, or universals, emerge from the extensive diversity found across the world's languages constitutes a central question for linguistics and cognitive science. Recent challenges to a fundamental assumption of generative linguistics-that universal properties of the human language acquisition faculty constrain the types of grammatical systems which can occur-suggest the need for new types of empirical evidence connecting typology to biases of learners. Using an artificial language learning paradigm in which adult subjects are exposed to a mix of grammatical systems (similar to a period of linguistic change), we show that learners' biases mirror a word-order universal, first proposed by Joseph Greenberg, which constrains typological patterns of adjective, numeral, and noun ordering. We briefly summarize the results of a probabilistic model of the hypothesized biases and their effect on learning, and discuss the broader implications of the results for current theories of the origins of cross-linguistic word-order preferences.

  11. Hindsight Bias and Developing Theories of Mind

    PubMed Central

    Bernstein, Daniel M.; Atance, Cristina; Meltzoff, Andrew N.; Loftus, Geoffrey R.

    2013-01-01

    Although hindsight bias (the “I knew it all along” phenomenon) has been documented in adults, its development has not been investigated. This is despite the fact that hindsight bias errors closely resemble the errors children make on theory of mind (ToM) tasks. Two main goals of the present work were to (a) create a battery of hindsight tasks for preschoolers, and (b) assess the relation between children’s performance on these and ToM tasks. In two experiments involving 144 preschoolers, 3-, 4-, and 5-year olds exhibited strong hindsight bias. Performance on hindsight and ToM tasks was significantly correlated independent of age, language ability, and inhibitory control. These findings contribute to a more comprehensive account of perspective taking across the lifespan. PMID:17650144

  12. Cosmology of biased discrete symmetry breaking

    NASA Technical Reports Server (NTRS)

    Gelmini, Graciela B.; Gleiser, Marcelo; Kolb, Edward W.

    1988-01-01

    The cosmological consequences of spontaneous breaking of an approximate discrete symmetry are studied. The breaking leads to formation of proto-domains of false and true vacuum separated by domain walls of thickness determined by the mass scale of the model. The cosmological evolution of the walls is extremely sensitive to the magnitude of the biasing; several scenarios are possible, depending on the interplay between the surface tension on the walls and the volume pressure from the biasing. Walls may disappear almost immediately after they form, or may live long enough to dominate the energy density of the Universe and cause power-law inflation. Limits are obtained on the biasing that characterizes each possible scenario.

  13. Attentional biases and vulnerability to depression.

    PubMed

    Gallardo Pérez, M; Baños Rivera, R M; Belloch Fuster, A; Ruipérez Rodríguez, M A

    1999-05-01

    This study was designed to examine selective processing of emotional information in depression. It focuses on possible attentional biases in depression, and whether such biases constitute a cognitive vulnerability factor to suffer from the disorder or, on the contrary, they reflect a feature associated exclusively with the clinical level of depression. 81 participants were included in the study: 15 with a diagnosis of Major Depression; 17 were diagnosed as Dysthymia; 11 participants scored over 18 in the Beck Depression Inventory (Beck, Rush, Shaw, & Emery, 1979); 15 participants, in whom a sad mood state was induced by an experimental mood induction (Velten technique + music, or biographical recall + music); and 23 participants as a normal-control group. All participants were presented with the emotional Stroop task. The data indicated that attentional bias was only present in the group of patients with Major Depression, so it does not seem to be a cognitive vulnerability factor for this disorder.

  14. Development of the first-mention bias.

    PubMed

    Hartshorne, Joshua K; Nappa, Rebecca; Snedeker, Jesse

    2015-03-01

    In many contexts, pronouns are interpreted as referring to the character mentioned first in the previous sentence, an effect called the 'first-mention bias'. While adults can rapidly use the first-mention bias to guide pronoun interpretation, it is unclear when this bias emerges during development. Curiously, experiments with children between two and three years old show successful use of order of mention, while experiments with older children (four to five years old) do not. While this could suggest U-shaped development, it could also reflect differences in the methodologies employed. We show that children can indeed use first-mention information, but do so too slowly to have been detected in previous work reporting null results. Comparison across the present and previously published studies suggests that the speed at which children deploy first-mention information increases greatly during the preschool years.

  15. Information-processing bias in social phobia.

    PubMed

    Hirsch, Colette R; Clark, David M

    2004-11-01

    Social phobia is a persistent disorder that is unlikely to be maintained by avoidance alone. One reason for the enduring nature of social phobia may be the way individuals with the disorder process social information. It is important for those involved in social phobia to have an understanding of information-processing biases, because it has the potential to guide psychological interventions. In this review of social phobia, probability and cost estimates of social situations are examined, interpretive biases are evaluated and findings relating to memory and negative imagery are also reviewed. The clinical implications of social-phobia-related information-processing biases are discussed and possible avenues for future research are outlined.

  16. Epidemic spreading driven by biased random walks

    NASA Astrophysics Data System (ADS)

    Pu, Cunlai; Li, Siyuan; Yang, Jian

    2015-08-01

    Random walk is one of the basic mechanisms of many network-related applications. In this paper, we study the dynamics of epidemic spreading driven by biased random walks in complex networks. In our epidemic model, infected nodes send out infection packets by biased random walks to their neighbor nodes, and this causes the infection of susceptible nodes that receive the packets. Infected nodes recover from the infection at a constant rate λ, and will not be infected again after recovery. We obtain the largest instantaneous number of infected nodes and the largest number of ever-infected nodes respectively, by tuning the parameter α of the biased random walks. Simulation results on model and real-world networks show that spread of the epidemic becomes intense and widespread with increase of either delivery capacity of infected nodes, average node degree, or homogeneity of node degree distribution.

  17. Recognition bias and the physical attractiveness stereotype.

    PubMed

    Rohner, Jean-Christophe; Rasmussen, Anders

    2012-06-01

    Previous studies have found a recognition bias for information consistent with the physical attractiveness stereotype (PAS), in which participants believe that they remember that attractive individuals have positive qualities and that unattractive individuals have negative qualities, regardless of what information actually occurred. The purpose of this research was to examine whether recognition bias for PAS congruent information is replicable and invariant across a variety of conditions (i.e. generalizable). The effects of nine different moderator variables were examined in two experiments. With a few exceptions, the effect of PAS congruence on recognition bias was independent of the moderator variables. The results suggest that the tendency to believe that one remembers information consistent with the physical attractiveness stereotype is a robust phenomenon. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

  18. Clustering: how much bias do we need?

    PubMed

    Lorimer, Tom; Held, Jenny; Stoop, Ruedi

    2017-06-28

    Scientific investigations in medicine and beyond increasingly require observations to be described by more features than can be simultaneously visualized. Simply reducing the dimensionality by projections destroys essential relationships in the data. Similarly, traditional clustering algorithms introduce data bias that prevents detection of natural structures expected from generic nonlinear processes. We examine how these problems can best be addressed, where in particular we focus on two recent clustering approaches, Phenograph and Hebbian learning clustering, applied to synthetic and natural data examples. Our results reveal that already for very basic questions, minimizing clustering bias is essential, but that results can benefit further from biased post-processing.This article is part of the themed issue 'Mathematical methods in medicine: neuroscience, cardiology and pathology'. © 2017 The Author(s).

  19. Uncovering racial bias in nursing fundamentals textbooks.

    PubMed

    Byrne, M M

    2001-01-01

    This article describes research that sought to identify and critique selected content areas from three nursing fundamentals textbooks for the presence or absence of racial bias embedded in the portrayal of African Americans. The analyzed content areas were the history of nursing, cultural content, and physical assessment/hygiene parameters. A researcher-developed guide was used for data collection and analysis of textual language, illustrations, linguistics, and references. A thematic analysis resulted in I I themes reflecting the portrayal of African Americans in these sampled textbooks. An interpretive analysis with a lens of Sadker and Sadker's categories of bias, along with other literary and theoretical contexts, were used to explore for the presence or absence of racial bias. Recommendations for nursing education are provided.

  20. Covariation bias in panic-prone individuals.

    PubMed

    Pauli, P; Montoya, P; Martz, G E

    1996-11-01

    Covariation estimates between fear-relevant (FR; emergency situations) or fear-irrelevant (FI; mushrooms and nudes) stimuli and an aversive outcome (electrical shock) were examined in 10 high-fear (panic-prone) and 10 low-fear respondents. When the relation between slide category and outcome was random (illusory correlation), only high-fear participants markedly overestimated the contingency between FR slides and shocks. However, when there was a high contingency of shocks following FR stimuli (83%) and a low contingency of shocks following FI stimuli (17%), the group difference vanished. Reversal of contingencies back to random induced a covariation bias for FR slides in high- and low-fear respondents. Results indicate that panic-prone respondents show a covariation bias for FR stimuli and that the experience of a high contingency between FR slides and aversive outcomes may foster such a covariation bias even in low-fear respondents.

  1. Lateral bias in theatre-seat choice.

    PubMed

    Harms, Victoria; Reese, Miriam; Elias, Lorin J

    2014-01-01

    Examples of behavioural asymmetries are common in the range of human behaviour; even when faced with a symmetrical environment people demonstrate reliable asymmetries in behaviours like gesturing, cradling, and even seating. One such asymmetry is the observation that participants tend to choose seats to the right of the screen when asked to select their preferred seating location in a movie theatre. However, these results are based on seat selection using a seating chart rather than examining real seat choice behaviour in the theatre context. This study investigated the real-world seating patterns of theatre patrons during actual film screenings. Analysis of bias scores calculated using photographs of theatre patrons revealed a significant bias to choose seats on the right side of the theatre. These findings are consistent with the prior research in the area and confirm that the seating bias observed when seats are selected from a chart accurately reflects real-world seating behaviour.

  2. Verb biases are shaped through lifelong learning.

    PubMed

    Ryskin, Rachel A; Qi, Zhenghan; Duff, Melissa C; Brown-Schmidt, Sarah

    2017-05-01

    Verbs often participate in more than 1 syntactic structure, but individual verbs can be biased in terms of whether they are used more often with 1 structure or the other. For instance, in a sentence such as "Bop the bunny with the flower," the phrase "with the flower" is more likely to indicate an instrument with which to "bop," rather than which "bunny" to bop. Conversely, in a sentence such as "Choose the cow with the flower," the phrase "with the flower" is more likely to indicate which "cow" to choose. An open question is where these biases come from and whether they continue to be shaped in adulthood in a way that has lasting consequences for real-time processing of language. In Experiment 1 we replicated previous findings that these language-wide biases guide online syntactic processing in a computer-based visual-world paradigm. In Experiment 2, we tested the malleability of these biases by exposing adults to initially unbiased verbs situated in unambiguous contexts that led to either instrument or modifier interpretations. During test, participants interpreted sentences containing either modifier- or instrument-trained verbs in ambiguous contexts. Eye-movement and action data show that participants' considerations of the candidate interpretations of the ambiguous with-phrases were guided by the newly learned verb biases. These results suggest that co-occurrence information about specific verbs and syntactic structures embedded in language experiences plays a role in forming, and continuously shaping, the verb biases that constitute a part of the broader representation of the language. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. Measuring non-local Lagrangian peak bias

    NASA Astrophysics Data System (ADS)

    Biagetti, Matteo; Chan, Kwan Chuen; Desjacques, Vincent; Paranjape, Aseem

    2014-06-01

    We investigate non-local Lagrangian bias contributions involving gradients of the linear density field, for which we have predictions from the excursion set peak formalism. We begin by writing down a bias expansion which includes all the bias terms, including the non-local ones. Having checked that the model furnishes a reasonable fit to the halo mass function, we develop a one-point cross-correlation technique to measure bias factors associated with χ2-distributed quantities. We validate the method with numerical realizations of peaks of Gaussian random fields before we apply it to N-body simulations. We focus on the lowest (quadratic) order non-local contributions -2χ _{10}(k_1\\cdot k_2) and χ _{01}[3(k_1\\cdot k_2)^2-k_1^2 k_2^2], where k_1, k_2 are wave modes. We can reproduce our measurement of χ10 if we allow for an offset between the Lagrangian halo centre-of-mass and the peak position. The sign and magnitude of χ10 is consistent with Lagrangian haloes sitting near linear density maxima. The resulting contribution to the halo bias can safely be ignored for M = 1013 M⊙ h-1, but could become relevant at larger halo masses. For the second non-local bias χ01 however, we measure a much larger magnitude than predicted by our model. We speculate that some of this discrepancy might originate from non-local Lagrangian contributions induced by non-spherical collapse.

  4. Reappraisal Modulates Attentional Bias to Angry Faces

    PubMed Central

    Kim, Shin Ah; Kim, Hackjin; Kim, Sang Hee

    2016-01-01

    Heightened attentional bias to emotional information is one of the main characteristics of disorders related to emotion dysregulation such as anxiety, depression, and substance abuse. Although reappraisal, an emotion regulation strategy, is known to effectively modulate subjective experience of emotions, it remains unknown whether reappraisal can alter attentional biases to emotional information. In the current research, we investigated the influence of instruction-induced state reappraisal (Study 1) and trait reappraisal (Study 2) on attentional biases to happy and angry faces. In Study 1, healthy young women were recruited and randomly assigned to one of the three groups: up-, down-, and no-regulation. Participants were instructed to reappraise their emotions to increase and decrease emotional experience while viewing an emotionally negative film clip. Attentional bias was assessed with a dot-probe task with pictures of angry and happy facial expressions. In Study 2, a separate group of healthy young men and women participated. Participants’ trait reappraisal and suppression as well as state and trait anxiety were assessed. A dot-probe task was completed by all participants. Statistical tests in Study 1 revealed that participants who reappraised to decrease negative emotions while viewing an emotionally negative film clip had reduced attentional bias to subsequently presented angry faces compared to participants who reappraised to increase negative emotions. Multiple regression analyses in Study 2 revealed that trait reappraisal predicted slower orienting toward angry faces, whereas state anxiety predicted slower disengagement from angry faces. Interestingly, trait suppression predicted slower disengagement from happy faces. Taken together, these results suggest that both instruction-induced state reappraisal and trait reappraisal are linked to reduced attentional bias to negative information and contribute to better understanding of how everyday emotion

  5. Biasing of Capacitive Micromachined Ultrasonic Transducers.

    PubMed

    Caliano, Giosue; Matrone, Giulia; Savoia, Alessandro Stuart

    2017-02-01

    Capacitive micromachined ultrasonic transducers (CMUTs) represent an effective alternative to piezoelectric transducers for medical ultrasound imaging applications. They are microelectromechanical devices fabricated using silicon micromachining techniques, developed in the last two decades in many laboratories. The interest for this novel transducer technology relies on its full compatibility with standard integrated circuit technology that makes it possible to integrate on the same chip the transducers and the electronics, thus enabling the realization of extremely low-cost and high-performance devices, including both 1-D or 2-D arrays. Being capacitive transducers, CMUTs require a high bias voltage to be properly operated in pulse-echo imaging applications. The typical bias supply residual ripple of high-quality high-voltage (HV) generators is in the millivolt range, which is comparable with the amplitude of the received echo signals, and it is particularly difficult to minimize. The aim of this paper is to analyze the classical CMUT biasing circuits, highlighting the features of each one, and to propose two novel HV generator architectures optimized for CMUT biasing applications. The first circuit proposed is an ultralow-residual ripple (<5 [Formula: see text]) HV generator that uses an extremely stable sinusoidal power oscillator topology. The second circuit employs a commercially available integrated step-up converter characterized by a particularly efficient switching topology. The circuit is used to bias the CMUT by charging a buffer capacitor synchronously with the pulsing sequence, thus reducing the impact of the switching noise on the received echo signals. The small area of the circuit (about 1.5 cm(2)) makes it possible to generate the bias voltage inside the probe, very close to the CMUT, making the proposed solution attractive for portable applications. Measurements and experiments are shown to demonstrate the effectiveness of the new approaches

  6. Possible biases in heritability estimates from intraclass correlation.

    PubMed

    Ponzoni, R W; James, J W

    1978-01-01

    There is an inherent bias in intraclass correlations since the expectation of a ratio does not equal the ratio of expectations. A simple accurate approximation for this bias is derived, and it is found that the inherent bias is usually negligible. Selection of sires is known to bias half-sib heritability estimates, and appropriate formulae are given and discussed.

  7. On the power of the test for cluster bias.

    PubMed

    Jak, Suzanne; Oort, Frans J

    2015-11-01

    Cluster bias refers to measurement bias with respect to the clustering variable in multilevel data. The absence of cluster bias implies absence of bias with respect to any cluster-level (level 2) variable. The variables that possibly cause the bias do not have to be measured to test for cluster bias. Therefore, the test for cluster bias serves as a global test of measurement bias with respect to any level 2 variable. However, the validity of the global test depends on the Type I and Type II error rates of the test. We compare the performance of the test for cluster bias with the restricted factor analysis (RFA) test, which can be used if the variable that leads to measurement bias is measured. It appeared that the RFA test has considerably more power than the test for cluster bias. However, the false positive rates of the test for cluster bias were generally around the expected values, while the RFA test showed unacceptably high false positive rates in some conditions. We conclude that if no significant cluster bias is found, still significant bias with respect to a level 2 violator can be detected with an RFA model. Although the test for cluster bias is less powerful, an advantage of the test is that the cause of the bias does not need to be measured, or even known.

  8. Perception Accuracy of Biases in Self and in Others

    ERIC Educational Resources Information Center

    Brycz, Hanna

    2011-01-01

    Three studies showed that the group of observers accurately recognized biases in other people's behaviors while the group of actors was unable to detect the same biases in their own behaviors. The logic and inevitability of biases influenced the estimations of the former. Biases which were positive, beneficial, logical and non-threatening for the…

  9. Recursive bias estimation and L2 boosting

    SciTech Connect

    Hengartner, Nicolas W; Cornillon, Pierre - Andre; Matzner - Lober, Eric

    2009-01-01

    This paper presents a general iterative bias correction procedure for regression smoothers. This bias reduction schema is shown to correspond operationally to the L{sub 2} Boosting algorithm and provides a new statistical interpretation for L{sub 2} Boosting. We analyze the behavior of the Boosting algorithm applied to common smoothers S which we show depend on the spectrum of I - S. We present examples of common smoother for which Boosting generates a divergent sequence. The statistical interpretation suggest combining algorithm with an appropriate stopping rule for the iterative procedure. Finally we illustrate the practical finite sample performances of the iterative smoother via a simulation study.

  10. Local bias-induced phase transitions

    SciTech Connect

    Seal, Katyayani; Baddorf, Arthur P.; Jesse, Stephen; Kalinin, Sergei V.; Nikiforov, Maxim; Proksch, Roger; Rodriguez, Brian J.; Maksymovych, Petro; Kholkin, Andrei L.

    2008-11-27

    Electrical bias-induced phase transitions underpin a wide range of applications from data storage to energy generation and conversion. The mechanisms behind these transitions are often quite complex and in many cases are extremely sensitive to local defects that act as centers for local transformations or pinning. Furthermore, using ferroelectrics as an example, we review methods for probing bias-induced phase transitions and discuss the current limitations and challenges for extending the methods to field-induced phase transitions and electrochemical reactions in energy storage, biological and molecular systems.

  11. Antiferromagnetic spin flop and exchange bias

    SciTech Connect

    Nogues, J.; Morellon, L.; Leighton, C.; Ibarra, M. R.; Schuller, Ivan K.

    2000-03-01

    The effect of the antiferromagnetic spin flop on exchange bias has been investigated in antiferromagnetic (MnF{sub 2})-ferromagnetic (Fe) bilayers. Cooling and measuring in fields larger than the antiferromagnetic spin-flop field, H{sub SF}, causes an irreversible reduction of the magnitude of the exchange bias field, H{sub E}. This indicates that, contrary to what is normally assumed, the interface spin structure does not remain ''frozen in'' below T{sub N} if large enough fields are applied. (c) 2000 The American Physical Society.

  12. Local bias-induced phase transitions

    DOE PAGES

    Seal, Katyayani; Baddorf, Arthur P.; Jesse, Stephen; ...

    2008-11-27

    Electrical bias-induced phase transitions underpin a wide range of applications from data storage to energy generation and conversion. The mechanisms behind these transitions are often quite complex and in many cases are extremely sensitive to local defects that act as centers for local transformations or pinning. Furthermore, using ferroelectrics as an example, we review methods for probing bias-induced phase transitions and discuss the current limitations and challenges for extending the methods to field-induced phase transitions and electrochemical reactions in energy storage, biological and molecular systems.

  13. Min-Max Bias Robust Regression.

    DTIC Science & Technology

    1987-08-01

    2 UL uIImImmIIIEllmlllllllll llEllllhllllEI El 1 .1 25 11111 -.4 ___ . .. . . N ~ . MIN- MAX BIAS ROBUST REGRESSION by R. D. Martin V. J. Yohai R. H...shown than an S-estimate based on a jump-function type p solves the n- max bias problem for the class of NI-estimates with very general scale. This...5, (X() -- .5 and the rin- max estimator approaches the least median of squared residuals estimator introduced by Rousseeuw [J. Am. Statist. Assoc

  14. Correlation between exchange bias and pinned interfacialspins

    SciTech Connect

    Ohldag, H.; Scholl, A.; Nolting, F.; Arenholz, E.; Maat, S.; Young, A.T.; Carey, M.; Stohr, J.

    2003-07-01

    Using x-ray magnetic circular dichroism, we have detectedthe very interfacial spins that are responsible for the horizontal loopshift in three different exchange bias sandwiches, chosen because oftheir potential for device applications. The "pinned" uncompensatedinterfacial spins constitute only a fraction of a monolayer and do notrotate in an external magnetic field since they are tightly locked to theantiferromagnetic lattice. A simple extension of the Meiklejohn and Beanmodel is proposed to account quantitatively for the exchange bias fieldsin the three studied systems from the experimentally determined number ofpinned moments and their sizes.

  15. Pseudo exchange bias due to rotational anisotropy

    NASA Astrophysics Data System (ADS)

    Ehrmann, A.; Komraus, S.; Blachowicz, T.; Domino, K.; Nees, M. K.; Jakobs, P. J.; Leiste, H.; Mathes, M.; Schaarschmidt, M.

    2016-08-01

    Ferromagnetic nanostructure arrays with particle dimensions between 160 nm and 400 nm were created by electron-beam lithography. The permalloy structures consist of rectangular-shaped walls around a square open space. While measuring their magnetic properties using the Magneto-Optical Kerr Effect (MOKE), in some angular regions an exchange bias (EB) seemed to appear. This paper gives an overview of possible reasons for this "pseudo exchange bias" and shows experimentally and by means of micromagnetic simulations that this effect can be attributed to unintentionally measuring minor loops.

  16. Microwave nanotube transistor operation at high bias

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Rutherglen, C.; Burke, P. J.

    2006-06-01

    We measure the small signal, 1GHz source-drain dynamical conductance of a back-gated single-walled carbon nanotube field effect transistor at both low and high dc bias voltages. At all bias voltages, the intrinsic device dynamical conductance at 1GHz is identical to the low frequency dynamical conductance, consistent with the prediction of a cutoff frequency much higher than 1GHz. This work represents a significant step towards a full characterization of a nanotube transistor for rf and microwave amplifiers.

  17. Best Practices in Hiring: Addressing Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Simpson, Caroline E.

    2012-01-01

    Research has shown that implementing certain hiring practices will increase diversity in the workplace while enhancing academic quality. All of these practices rely on addressing the issue of 'unconscious bias.' A brief overview of unconscious bias--what it is, how it works, and simple measures to counter it--will be presented. Successful strategies, actions, and recommendations for implementing best recruiting and hiring practices, which have been proven to enhance academic excellence by ensuring a deep and diverse applicant pool, will also be presented.

  18. Countering cognitive biases in minimising low value care.

    PubMed

    Scott, Ian A; Soon, Jason; Elshaug, Adam G; Lindner, Robyn

    2017-05-15

    Cognitive biases in decision making may make it difficult for clinicians to reconcile evidence of overuse with highly ingrained prior beliefs and intuition. Such biases can predispose clinicians towards low value care and may limit the impact of recently launched campaigns aimed at reducing such care. Commonly encountered biases comprise commission bias, illusion of control, impact bias, availability bias, ambiguity bias, extrapolation bias, endowment effects, sunken cost bias and groupthink. Various strategies may be used to counter such biases, including cognitive huddles, narratives of patient harm, value considerations in clinical assessments, defining acceptable levels of risk of adverse outcomes, substitution, reflective practice and role modelling, normalisation of deviance, nudge techniques and shared decision making. These debiasing strategies have considerable face validity and, for some, effectiveness in reducing low value care has been shown in randomised trials.

  19. Trends in Environmental Analysis

    SciTech Connect

    Koester, C J; Moulik, A

    2005-03-31

    This article discusses developments in environmental analytical chemistry that occurred in the years of 2003 and 2004. References were found by searching the ''Science Citation Index and Current Contents''. As in our review of two years ago (A1), techniques are highlighted that represent current trends and state-of-the-art technologies in the sampling, extraction, separation, and detection of trace concentrations, low-part-per-billion and less, of organic, inorganic, and organometallic contaminants in environmental samples. New analytes of interest are also reviewed, the detections of which are made possible by recently developed analytical instruments and methods.

  20. Modern trends in lipomodeling

    PubMed Central

    El-Sabbagh, Ahmed Hassan

    2017-01-01

    Lipomodeling is the process of relocating autologous fat to change the shape, volume, consistency, and profile of tissues, with the aim of reconstructing, rejuvenating, and regenerating body features. There have been several important advancements in lipomodeling procedures during the last thirty years. Four clinical steps are important for the success of engraftment: fat harvesting, fat processing, fat reinjection, and preconditioning of the recipient site. With the discovery of adipose derived stem cells and dedifferentiated cells, fat cells become a major tool of regenerative medicine. This article reviews recent trends in lipomodeling trying to understand most of the issues in this field. PMID:28401032

  1. Trends in PET imaging

    SciTech Connect

    Moses, William W.

    2000-11-01

    Positron Emission Tomography (PET) imaging is a well established method for obtaining information on the status of certain organs within the human body or in animals. This paper presents an overview of recent trends PET instrumentation. Significant effort is being expended to develop new PET detector modules, especially those capable of measuring depth of interaction. This is aided by recent advances in scintillator and pixellated photodetector technology. The other significant area of effort is development of special purpose PET cameras (such as for imaging breast cancer or small animals) or cameras that have the ability to image in more than one modality (such as PET / SPECT or PET / X-Ray CT).

  2. [Trends in surgery].

    PubMed

    Cerantola, Y; Christoforidis, D; Halkic, N; Matter, M; Romy, S; Suter, M; Tempia-Caliera, A; Demartines, N; Givel, J-C

    2009-01-21

    More than the number of real novelties, trends and preliminary results characterise the annual development in surgery. The wealth and diversity of topics to be covered require arbitrary choices, therefore not necessarily complete. The constant development of choledocolithiasis management, dominated by minimal invasive technology, treatments of unusual nature of two frequent proctological conditions, fistulae and haemorrhoids, the increasing importance of metabolic bariatric surgery, as well as the strict rules of effective melanoma treatment, represent as many directions in which the operating procedure, although unseen, continue to gain quality and security.

  3. Trends in Neurocognitive Aging

    PubMed Central

    Grady, Cheryl

    2013-01-01

    Preface The availability of neuroimaging technology has spurred a marked increase in the human cognitive neuroscience literature, including the study of cognitive aging. Although there is a growing consensus that the aging brain retains considerable plasticity of function, currently measured primarily by means of functional magnetic resonance imaging, it is less clear how age differences in brain activity relate to cognitive performance. The field also is hampered by the complexity of the aging process itself and the large number of factors that are influenced by age. In this review, current trends and unresolved issues in the cognitive neuroscience of aging are discussed. PMID:22714020

  4. New trends in emerging pathogens.

    PubMed

    Skovgaard, Niels

    2007-12-15

    pathogen and swine may serve as a source of infection in human, a most challenging issue in greater part of the world raising pigs. Tick-borne encephalitis virus infection, either thick borne or caused by consumption of raw milk, is an increasing trend in the industrialized part of the world. Consumer awareness, ethics of food, sustainability in food production, and trust in foods, are of growing importance to the consumer. The reaction of the consumer to new technology, such as nanotechnology, is unpredictable. Many efforts should be devoted to communication of non-biased information to both the food producers as well as the consumer.

  5. Bias structure to efficiently package a magnetic bubble domain device

    NASA Technical Reports Server (NTRS)

    Chen, Thomas T. (Inventor)

    1978-01-01

    A single, compact bias structure to efficiently package a plurality of magnetic bubble domain device chips having different bias requirements. The vertical magnetic field distribution within the bias structure air gap is selectively controlled by a magnetically soft field adjusting assembly suitably attached within the bias structure. The size and configuration of the field adjusting assembly tailors local field variations within the air gap to correspond with the bias requirements of the bubble domain chips disposed therein.

  6. Maternal Anxiety Predicts Attentional Bias Towards Threat in Infancy.

    PubMed

    Morales, Santiago; Brown, Kayla M; Taber-Thomas, Bradley C; LoBue, Vanessa; Buss, Kristin A; Pérez-Edgar, Koraly E

    2017-02-16

    Although cognitive theories of psychopathology suggest that attention bias toward threat plays a role in the etiology and maintenance of anxiety, there is relatively little evidence regarding individual differences in the earliest development of attention bias toward threat. The current study examines attention bias toward threat during its potential first emergence by evaluating the relations between attention bias and known risk factors of anxiety (i.e., temperamental negative affect and maternal anxiety). We measured attention bias to emotional faces in infants (N = 98; 57 male) ages 4 to 24 months during an attention disengagement eye-tracking paradigm. We hypothesized that (a) there would be an attentional bias toward threat in the full sample of infants, replicating previous studies; (b) attentional bias toward threat would be positively related to maternal anxiety; and (c) attention bias toward threat would be positively related to temperamental negative affect. Finally, (d) we explored the potential interaction between temperament and maternal anxiety in predicting attention bias toward threat. We found that attention bias to the affective faces did not change with age, and that bias was not related to temperament. However, attention bias to threat, but not attention bias to happy faces, was positively related to maternal anxiety, such that higher maternal anxiety predicted a larger attention bias for all infants. These findings provide support for attention bias as a putative early mechanism by which early markers of risk are associated with socioemotional development. (PsycINFO Database Record

  7. Correction of biased climate simulated by biased physics through parameter estimation in an intermediate coupled model

    NASA Astrophysics Data System (ADS)

    Zhang, Xuefeng; Zhang, Shaoqing; Liu, Zhengyu; Wu, Xinrong; Han, Guijun

    2016-09-01

    Imperfect physical parameterization schemes are an important source of model bias in a coupled model and adversely impact the performance of model simulation. With a coupled ocean-atmosphere-land model of intermediate complexity, the impact of imperfect parameter estimation on model simulation with biased physics has been studied. Here, the biased physics is induced by using different outgoing longwave radiation schemes in the assimilation and "truth" models. To mitigate model bias, the parameters employed in the biased longwave radiation scheme are optimized using three different methods: least-squares parameter fitting (LSPF), single-valued parameter estimation and geography-dependent parameter optimization (GPO), the last two of which belong to the coupled model parameter estimation (CMPE) method. While the traditional LSPF method is able to improve the performance of coupled model simulations, the optimized parameter values from the CMPE, which uses the coupled model dynamics to project observational information onto the parameters, further reduce the bias of the simulated climate arising from biased physics. Further, parameters estimated by the GPO method can properly capture the climate-scale signal to improve the simulation of climate variability. These results suggest that the physical parameter estimation via the CMPE scheme is an effective approach to restrain the model climate drift during decadal climate predictions using coupled general circulation models.

  8. Double propensity-score adjustment: A solution to design bias or bias due to incomplete matching.

    PubMed

    Austin, Peter C

    2017-02-01

    Propensity-score matching is frequently used to reduce the effects of confounding when using observational data to estimate the effects of treatments. Matching allows one to estimate the average effect of treatment in the treated. Rosenbaum and Rubin coined the term "bias due to incomplete matching" to describe the bias that can occur when some treated subjects are excluded from the matched sample because no appropriate control subject was available. The presence of incomplete matching raises important questions around the generalizability of estimated treatment effects to the entire population of treated subjects. We describe an analytic solution to address the bias due to incomplete matching. Our method is based on using optimal or nearest neighbor matching, rather than caliper matching (which frequently results in the exclusion of some treated subjects). Within the sample matched on the propensity score, covariate adjustment using the propensity score is then employed to impute missing potential outcomes under lack of treatment for each treated subject. Using Monte Carlo simulations, we found that the proposed method resulted in estimates of treatment effect that were essentially unbiased. This method resulted in decreased bias compared to caliper matching alone and compared to either optimal matching or nearest neighbor matching alone. Caliper matching alone resulted in design bias or bias due to incomplete matching, while optimal matching or nearest neighbor matching alone resulted in bias due to residual confounding. The proposed method also tended to result in estimates with decreased mean squared error compared to when caliper matching was used.

  9. Double propensity-score adjustment: A solution to design bias or bias due to incomplete matching

    PubMed Central

    2016-01-01

    Propensity-score matching is frequently used to reduce the effects of confounding when using observational data to estimate the effects of treatments. Matching allows one to estimate the average effect of treatment in the treated. Rosenbaum and Rubin coined the term “bias due to incomplete matching” to describe the bias that can occur when some treated subjects are excluded from the matched sample because no appropriate control subject was available. The presence of incomplete matching raises important questions around the generalizability of estimated treatment effects to the entire population of treated subjects. We describe an analytic solution to address the bias due to incomplete matching. Our method is based on using optimal or nearest neighbor matching, rather than caliper matching (which frequently results in the exclusion of some treated subjects). Within the sample matched on the propensity score, covariate adjustment using the propensity score is then employed to impute missing potential outcomes under lack of treatment for each treated subject. Using Monte Carlo simulations, we found that the proposed method resulted in estimates of treatment effect that were essentially unbiased. This method resulted in decreased bias compared to caliper matching alone and compared to either optimal matching or nearest neighbor matching alone. Caliper matching alone resulted in design bias or bias due to incomplete matching, while optimal matching or nearest neighbor matching alone resulted in bias due to residual confounding. The proposed method also tended to result in estimates with decreased mean squared error compared to when caliper matching was used. PMID:25038071

  10. Global trends, needs, issues.

    PubMed

    Kieffer, R G

    1998-01-01

    Worldwide, Pharmaceutical Plant Management struggles with the competing priorities of lowering costs, rising customer expectations, more demanding government regulations, and the need to reduce cycle times especially in the introduction of new products. All of this takes place in an environment of global competition, regulatory harmonization, mergers and downsizing, and employee insecurity. Employees are expected to do more with less, work with more sophisticated equipment and processes, take more personal responsibility for quality and productivity, work in teams, etc. In summary, we are talking about CHANGE, the speed of which will accelerate in the years to come. This presentation will discuss how some pharmaceutical plants are addressing these challenges. Examples will be given in the areas of validation, process reengineering, risk analysis, role of the quality function and people. It is my contention that most of the global trends today are insufficient to meet the challenges that we face. I hope that this presentation will generate some ideas on what the global trends should be.

  11. Bias and Obfuscation in Kendler's (2005) "Clarification"

    ERIC Educational Resources Information Center

    Schneider, Kirk J.

    2006-01-01

    This paper comments on the article "Psychology and Phenomenology: A Clarification" by H. H. Kendler. In this article, Kendler misrepresented contemporary existential-humanistic psychology and conventional (or natural) scientific psychology. With regard to the former, he presented a confused, unwittingly biased, and all-too-stereotypic picture.…

  12. Economic Costs of Bias-Based Bullying

    ERIC Educational Resources Information Center

    Baams, Laura; Talmage, Craig A.; Russell, Stephen T.

    2017-01-01

    Because many school districts receive funding based on student attendance, absenteeism results in a high cost for the public education system. This study shows the direct links between bias-based bullying, school absenteeism because of feeling unsafe at school, and loss of funds for school districts in California. Data from the 2011-2013…

  13. Biased Language: The Urge to Purge.

    ERIC Educational Resources Information Center

    Maculaitis, Jean D'Arcy

    Issues of social discrimination of all kinds and in all forms in teaching are discussed. Sexism, racism, ageism, bias by commission versus omission, other objectionable stereotypes, and the difference between accurate portrayal and the ideal are defined. Sixteen suggestions are given for choosing or developing language arts instructional materials…

  14. Exchange bias mediated by interfacial nanoparticles (invited)

    SciTech Connect

    Berkowitz, A. E.; Sinha, S. K.; Fullerton, E. E.; Smith, D. J.

    2015-05-07

    The objective of this study on the iconic exchange-bias bilayer Permalloy/CoO has been to identify those elements of the interfacial microstructure and accompanying magnetic properties that are responsible for the exchange-bias and hysteretic properties of this bilayer. Both epitaxial and polycrystalline samples were examined. X-ray and neutron reflectometry established that there existed an interfacial region, of width ∼1 nm, whose magnetic properties differed from those of Py or CoO. A model was developed for the interfacial microstructure that predicts all the relevant properties of this system; namely; the temperature and Permalloy thickness dependence of the exchange-bias, H{sub EX}, and coercivity, H{sub C}; the much smaller measured values of H{sub EX} from what was nominally expected; the different behavior of H{sub EX} and H{sub C} in epitaxial and polycrystalline bilayers. A surprising result is that the exchange-bias does not involve direct exchange-coupling between Permalloy and CoO, but rather is mediated by CoFe{sub 2}O{sub 4} nanoparticles in the interfacial region.

  15. Accounting for discovery bias in genomic prediction

    USDA-ARS?s Scientific Manuscript database

    Our objective was to evaluate an approach to mitigating discovery bias in genomic prediction. Accuracy may be improved by placing greater emphasis on regions of the genome expected to be more influential on a trait. Methods emphasizing regions result in a phenomenon known as “discovery bias” if info...

  16. Auditory perception bias in speech imitation

    PubMed Central

    Postma-Nilsenová, Marie; Postma, Eric

    2013-01-01

    In an experimental study, we explored the role of auditory perception bias in vocal pitch imitation. Psychoacoustic tasks involving a missing fundamental indicate that some listeners are attuned to the relationship between all the higher harmonics present in the signal, which supports their perception of the fundamental frequency (the primary acoustic correlate of pitch). Other listeners focus on the lowest harmonic constituents of the complex sound signal which may hamper the perception of the fundamental. These two listener types are referred to as fundamental and spectral listeners, respectively. We hypothesized that the individual differences in speakers' capacity to imitate F0 found in earlier studies, may at least partly be due to the capacity to extract information about F0 from the speech signal. Participants' auditory perception bias was determined with a standard missing fundamental perceptual test. Subsequently, speech data were collected in a shadowing task with two conditions, one with a full speech signal and one with high-pass filtered speech above 300 Hz. The results showed that perception bias toward fundamental frequency was related to the degree of F0 imitation. The effect was stronger in the condition with high-pass filtered speech. The experimental outcomes suggest advantages for fundamental listeners in communicative situations where F0 imitation is used as a behavioral cue. Future research needs to determine to what extent auditory perception bias may be related to other individual properties known to improve imitation, such as phonetic talent. PMID:24204361

  17. Superstition: a matter of bias, not detectability.

    PubMed

    Killeen, P R

    1978-01-06

    Pigeons discriminated between stimulus changes dependent on their pecking and stimulus changes occurring independently of their behavior. Their performance was accurate, and when the payoffs for "hits" and "correct rejections" were varied, their response bias varied in a fashion similar to that of human observers detecting signals in a background of noise.

  18. The Nature and Implication of Textbook Bias.

    ERIC Educational Resources Information Center

    Parsons, Jim

    Savage, blood-thirsty, drunk, monosyllabic, naked, and primitive are the stereotypes of Native Americans in textbooks. These stereotypes are so pervasive that they tend to be accepted uncritically by the rest of society. The evidence suggests that many textbooks are biased and, in a large number of cases, outright racist. The concept of…

  19. Does Verb Bias Modulate Syntactic Priming?

    ERIC Educational Resources Information Center

    Bernolet, Sarah; Hartsuiker, Robert J.

    2010-01-01

    In a corpus analysis of spontaneous speech Jaeger and Snider (2007) found that the strength of structural priming is correlated with verb alternation bias. This finding is consistent with an implicit learning account of syntactic priming: because the implicit learning model implemented by Chang (2002), Chang, Dell, and Bock (2006), and Chang,…

  20. Word Problems: Where Test Bias Creeps In.

    ERIC Educational Resources Information Center

    Chipman, Susan F.

    The problem of sex bias in mathematics word problems is discussed, with references to the appropriate literature. Word problems are assessed via cognitive science analysis of word problem solving. It has been suggested that five basic semantic relations are adequate to classify nearly all story problems, namely, change, combine, compare, vary, and…